furniture vs piece of furniture

furniture and piece of furniture both are nouns.

Word	Noun	Adjective	Verb	Adverb
furniture	Yes	No	No	No
piece of furniture	Yes	No	No	No

As nouns, furniture and piece of furniture are synonyms defined as:

furniture and piece of furniture: furnishings that make a room or other area ready for occupancy

Other synonyms of furniture include article of furniture.

furniture (noun)	piece of furniture (noun)
furnishings that make a room or other area ready for occupancy	furnishings that make a room or other area ready for occupancy