Bitcoin is a cryptocurrency, while blockchain is a distributed database. Bitcoin is powered by blockchain technology, but blockchain has found many uses beyond Bitcoin. Bitcoin promotes anonymity, while blockchain is about transparency. Bitcoin transactions are stored and transferred using a distributed ledger on a peer-to-peer network that is open, public and anonymous. Blockchain is the underpinning technology that maintains the Bitcoin transaction ledger. This is futher explained in the video below (source : Luno)