difference between mortar and plaster

Mortar is used in masonry to join stones, bricks, blocks etc. and plaster is used for plastering outside and inside walls. The difference between mortar and plaster lies in the ability of plaster to take on a better finish, which largely depends on the type of sand used in the mix. For plasters we use fine sand. However, the word mortar is used loosely to refer to both plasters and mortars.