http://en.wikipedia.org/wiki/Hash_list
In computer science, a hash list is typically a list of hashes of the data blocks in a file or set of files
An important use of hash lists is to make sure that data blocks received from other peers in a peer-to-peer network are received undamaged and unaltered, and to check that the other peers do not "lie" and send fake blocks.
http://en.wikipedia.org/wiki/Merkle_tree
A hash tree is a tree of hashes in which the leaves are hashes of data blocks in, for instance, a file or set of files. Nodes further up in the tree are the hashes of their respective children.