As others have pointed out: very little is different. Depending on if you include consensus in your use of "blockchain", there may be no difference whatsoever.
Currently it's a massively popular buzzword that frequently means very little in reality. It's just being tacked onto everything whether or not it makes sense because e.g. the Long Island Iced Tea company switched their name to "Long Blockchain" and immediately had massive stock gains: https://arstechnica.com/tech-policy/2017/12/iced-tea-company... . Even in the cases where it is technically accurate, it's rarely a good or useful idea... but it helps get funding.
So in practice, "blockchain" currently means "you will magically get rich". Technically it's almost always a Merkle tree, or a less efficient structure (e.g. Bitcoin's core "chain" is basically a linear version, which is dramatically less efficient to verify to the root for any given block... because it doesn't need that quality. Though it also uses Merkle trees within each block).
Currently it's a massively popular buzzword that frequently means very little in reality. It's just being tacked onto everything whether or not it makes sense because e.g. the Long Island Iced Tea company switched their name to "Long Blockchain" and immediately had massive stock gains: https://arstechnica.com/tech-policy/2017/12/iced-tea-company... . Even in the cases where it is technically accurate, it's rarely a good or useful idea... but it helps get funding.
So in practice, "blockchain" currently means "you will magically get rich". Technically it's almost always a Merkle tree, or a less efficient structure (e.g. Bitcoin's core "chain" is basically a linear version, which is dramatically less efficient to verify to the root for any given block... because it doesn't need that quality. Though it also uses Merkle trees within each block).