Confidential Transactions — At present, all Bitcoin transactions are completely public, albeit pseudonymous. Confidential Transactions, as the name implies, conceal the amount being transferred to all except the sender, the recipient, and others they designate. The resulting transaction size is significantly larger, but includes a sizable “memo” field that can be used to store transaction or other metadata, and is still smaller than eg Zerocoin.(Note that this isn’t as confidential as Zerocash, which conceals both the amount and the participants involved in any transaction, through the mighty near-magic of zk-Snarks. Mind you, Zerocash would require an esoteric invocation ritual to initiate its network. No, really. But that’s a subject for a separate post.)

The distributed Bitcoin mining network performs quadrillions of calculations every second that maintain the integrity of its blockchain. Other blockchains aren’t remotely as secure, but they innovate much faster. Sidechains, an innovation proposed and developed by the startup Blockstream, allow for the best of both worlds; the creation of new blockchains “pegged” to Bitcoin, so that value can be transferred between them, which can conceivably be automatically secured by Bitcoin miners via “merged mining.”

Blockstream is collaborating with industry leaders to create a Bitcoin micropayment system that supports high volumes of instant tiny payments using proportional transaction fees and that operates at the speed of light. We are now developing Bitcoin Lightning prototypes and creating consensus on interoperability. Our c-lightning implementation is the go-to code and specification for enterprise Lightning Network deployments on Bitcoin, and is what powers our easy-to-use Lightning Charge HTTP Rest API.

Aelf uses a consensus algorithm called DPoS (Delegated Proof of Stake) that takes the best of both cooperative and competitive consensus algorithms. DPoS uses votes from stakeholders to achieve consensus. The competitive part is larger stakeholders having an influence on their delegate of choice. The delegates that have the most votes will take their turn to produce a block cooperatively in a sequence. DPoS makes transactions permanent. A rollback isn’t possible so a confirmation can be fast. DPoS is also scalable because anyone can participate in the consensus. Additionally, DPoS is environmentally friendly because electricity isn’t wasted like in Proof of Work.
“We believe that public blockchains with censorship resistance have the potential to disrupt society, when private blockchains are merely a cost-efficiency tool for banking back offices. One can measure its potential in trillions of dollars, the other in billions. But as they are totally orthogonal, both can coexist in the same time, and therefore there is no need to oppose them as we can often see it.” 
Performance at scale: It is not uncommon for large businesses to process 100,000’s of transactions per second (TPS). Therefore, enterprise blockchains need to scale so that they can deliver performance accordingly. To achieve this, they can compartmentalize processes using containers or similar approaches. Read more about this requirement in this article “Enterprise blockchain ready to go live”.
Performance at scale: It is not uncommon for large businesses to process 100,000’s of transactions per second (TPS). Therefore, enterprise blockchains need to scale so that they can deliver performance accordingly. To achieve this, they can compartmentalize processes using containers or similar approaches. Read more about this requirement in this article “Enterprise blockchain ready to go live”.
Blockchains that are private or permissioned work similarly to public blockchains but with access controls that restrict those that can join the network, meaning it operates like a centralised database system of today that limits access to certain users. Private Blockchains have one or multiple entities that control the network, leading to the reliance on third-parties to transact. A well-known example would be Hyperledger.
Tú, o el usuario en cuestión de las sidechains, envía los bitcoins a una dirección Bitcoin específica, sabiendo que, una vez mandados, estarán fuera de tu control y fuera del control de cualquier otra persona. Estarán completamente inmovilizados y sólo se podrán desbloquear si alguien puede demostrar que no se están utilizando en ningún otro lugar.
“Private blockchains are valuable to solve efficiency, security and fraud problems within traditional financial institutions, but only incrementally. Private blockchains will not revolutionize the financial system. Public blockchains, however, hold the potential to replace most functions of traditional financial institutions with software, fundamentally reshaping the way the financial system works.” 
Blockchain-based smart contracts are proposed contracts that could be partially or fully executed or enforced without human interaction.[55] One of the main objectives of a smart contract is automated escrow. An IMF staff discussion reported that smart contracts based on blockchain technology might reduce moral hazards and optimize the use of contracts in general. But "no viable smart contract systems have yet emerged." Due to the lack of widespread use their legal status is unclear.[56]
Sidechains solve a lot of problems, but at what cost? The introduction of sidechains makes things even more complex and much harder to understand for those who are not actively involved in the blockchain space. This also divides assets, no more “one chain, one asset” adage, which further complicates things. And on a network level there are multiple independent unsynchronised blockchains interacting with each other.
People believe that permissioned means that only a select group of people can access the data and that’s the security feature. But it’s not. Since there is no real user data on the blockchain, (you) as a member of the public, can’t verify the actual content of it. This means that data resides in a location where corruption can stay undetected and data can be easily modified. So why does it even exist? Mainly because of the phenomena known as “hype surfing”; essentially reusing old technology and strapping a blockchain sticker on it gets IBM salesmen a foot in the door to institutions who can’t evaluate the technology accurately in the first place. Unfortunately, even some teams doing public token offerings started to sell this deeply flawed approach to the public.

Every node in a decentralized system has a copy of the blockchain. Data quality is maintained by massive database replication[8] and computational trust. No centralized "official" copy exists and no user is "trusted" more than any other.[4] Transactions are broadcast to the network using software. Messages are delivered on a best-effort basis. Mining nodes validate transactions,[22] add them to the block they are building, and then broadcast the completed block to other nodes.[24]:ch. 08 Blockchains use various time-stamping schemes, such as proof-of-work, to serialize changes.[34] Alternative consensus methods include proof-of-stake.[22] Growth of a decentralized blockchain is accompanied by the risk of centralization because the computer resources required to process larger amounts of data become more expensive.[35]

Transparency does not, however, mean that public blockchains are completely unhackable. Any time data enters a digital network, it is subject to security breaches and unethical uses. Although public blockchains looks to be highly secure right now, there are always going to be bad actors interested in exploiting weaknesses in the system. This is often through hacking methods that are difficult to predict and account for — so claims of one-hundred-percent security in any technology should always be read with a critical eye

Over the last year the concept of “private blockchains” has become very popular in the broader blockchain technology discussion. Essentially, instead of having a fully public and uncontrolled network and state machine secured by cryptoeconomics (eg. proof of work, proof of stake), it is also possible to create a system where access permissions are more tightly controlled, with rights to modify or even read the blockchain state restricted to a few users, while still maintaining many kinds of partial guarantees of authenticity and decentralization that blockchains provide. Such systems have been a primary focus of interest from financial institutions, and have in part led to a backlash from those who see such developments as either compromising the whole point of decentralization or being a desperate act of dinosaurish middlemen trying to stay relevant (or simply committing the crime of using a blockchain other than Bitcoin). However, for those who are in this fight simply because they want to figure out how to best serve humanity, or even pursue the more modest goal of serving their customers, what are the practical differences between the two styles?

A diferencia con la, hasta ahora, plataforma estrella de smart contracts Ethereum, otra de las diferencias más importantes de Lisk es que, en Lisk, cada aplicación corre sobre su propia sidechain y no sobre una única cadena, cómo es el caso de Ethereum. Por lo tanto, un entorno propio e independiente que podrá exprimir cada desarrollador para cada DAPP desarrollada con un backend en JS/NodeJS y un frontend HTML/CSS/JS.
At Iryo, we consider databases and blockchains that are not opened to the public to be insecure they, can easily be altered by the business running it, at their discretion and it goes against the ethos of the open and transparent cryptocurrency space. Designed to keep public out and introducing “trusted” middlemen, private chains forget that trusted third parties are security holes.
RSK is the first open-source smart contract platform with a 2-way peg to Bitcoin that also rewards the Bitcoin miners via merge-mining, allowing them to actively participate in the Smart Contract revolution. RSK goal is to add value and functionality to the Bitcoin ecosystem by enabling smart-contracts, near instant payments and higher-scalability.
Side-chain is another blockchain for one blockchain. To use side-chain of Bitcoin, for instance, you need to move BTC from the original chain to the side-chain. Then, BTC on the original chain is locked and the same amount of BTC on the side-chain appears. This is how BTC can be used/tested on another chain where we use some features different from the original ones.
Plasma, a project by Ethereum, uses this side chain concept. It encourages transactions to happen on side chains (or child chains). An authority governs each of the child chains. If the authority starts acting maliciously, anyone on the child chain can quit the child chain and take back their pegged assets on the main chain. It’s in its early stages of development but shows a lot of promise in handling some of Ethereum’s scalability issues.
The immense promise and accelerated development of permissioned blockchain technology, combined with intense business interest from a wide range of industries, is acting as a perfect stimulant for more and more enterprises to start rolling out blockchain networks into production. I envision these permissioned networks will soon directly or indirectly influence every facet of human enterprise.