upright piano vs pianoforte

upright piano and pianoforte both are nouns.

Word	Noun	Adjective	Verb	Adverb
upright piano	Yes	No	No	No
pianoforte	Yes	No	No	No

As nouns, pianoforte is a hypernym of upright piano; that is, pianoforte is a word with a broader meaning than upright piano:

upright piano: a piano with a vertical sounding board
pianoforte: a keyboard instrument that is played by depressing keys that cause hammers to strike tuned strings and produce sounds

Other hypernyms of upright piano include forte-piano, piano.

upright piano (noun)	pianoforte (noun)
a piano with a vertical sounding board	a keyboard instrument that is played by depressing keys that cause hammers to strike tuned strings and produce sounds