sideboard vs furniture

sideboard and furniture both are nouns.

Word	Noun	Adjective	Verb	Adverb
sideboard	Yes	No	No	No
furniture	Yes	No	No	No

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

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

Other hypernyms of sideboard include article of furniture, piece of furniture.

sideboard (noun)	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
a board that forms part of the side of a bed or crib
a removable board fitted on the side of a wagon to increase its capacity