Multichain is directly built from Bitcoin Core which power the bitcoins. Of course there are modifications to it. Multichain provides direct interface with many parameters and is basically used to make permissioned networks. And the major difference between multichain and other blockchain technologies is no use of smart contracts in multichain.

Also, Bitcoin is open network, Ethereum allows public network apps, hyperledger is used for building private blockchains and multichain for permissioned blockchains.