buffet vs piece of furniture

buffet and piece of furniture both are nouns.

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

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

buffet: a piece of furniture that stands at the side of a dining room; has shelves and drawers
piece of furniture: furnishings that make a room or other area ready for occupancy

Other hypernyms of buffet include article of furniture, furniture.

buffet (noun)	piece of furniture (noun)
a piece of furniture that stands at the side of a dining room; has shelves and drawers	furnishings that make a room or other area ready for occupancy
usually inexpensive bar
a meal set out on a buffet at which guests help themselves

buffet (verb)	piece of furniture (verb)
strike against forcefully
strike, beat repeatedly