Different types of blockchain
Not all blockchains are the same. Several current cryptocurrencies (also known as digital currencies) started with the Bitcoin code base, and many use the same blockchain. For example, Bitcoin and Litecoin use the same binary format for the blockchain but differ in the cryptography and consensus approaches. Zcash is a cryptocurrency that is based on an earlier version of Bitcoin but made major changes to support added anonymity and privacy. Permissioned blockchains such as Hyperledger, Chain, R3 Corda and BigchainDB use an underlying NoSQL database to store the blockchain data. Permissioned or private blockchains appoint authority to specific parties in the network to authenticate blockchain transactions through an access layer. While private blockchains do not require a consensus process, they are less disruptive because they depend more on a built-in authority.