What's the difference between a hash chain, transaction chain and a blockchain? Can anyone explain to me what the difference is between a hash chain, transaction chain and a blockchain?
A hash chain is a sequence of hashes of blocks. Each block consists of the hash of the previous block, and (optionally) some data. These can be seen a special case of a Merkle Tree, that is one with only a single branch.
A transaction chain is a hash chain with the data being lists of transactions, instead of arbitrary data.
A blockchain is a Merkle Tree with a consensus algorithm to determine which branch is the &quot;correct&quot; one. Typically other branches get discarded, but not always. E.G. git uses a Merkle Tree internally to verify the directed acyclic graph of commits, with a specially named branch (usually master or main) maintained by some user as the cannonical chain.
Cryptographically they're all identical, unless the consensus algorithm of a blockchain involves cryptography. Not all of them do, eg permissioned blockchains simply require authorization by the chain administrator to add a block.