drop cloth vs piece of cloth

drop cloth and piece of cloth both are nouns.

Word	Noun	Adjective	Verb	Adverb
drop cloth	Yes	No	No	No
piece of cloth	Yes	No	No	No

As nouns, piece of cloth is a hypernym of drop cloth; that is, piece of cloth is a word with a broader meaning than drop cloth:

drop cloth: a large piece of cloth laid over the floor or furniture while a room is being painted
piece of cloth: a separate part consisting of fabric

Other hypernyms of drop cloth include piece of material.

drop cloth (noun)	piece of cloth (noun)
a curtain that can be lowered and raised onto a stage from the flies; often used as background scenery	a separate part consisting of fabric
a large piece of cloth laid over the floor or furniture while a room is being painted