tempo vs allegro

tempo and allegro both are nouns.

Word	Noun	Adjective	Verb	Adverb
tempo	Yes	No	No	No
allegro	Yes	Yes	No	Yes

As nouns, allegro is a hyponym of tempo; that is, allegro is a word with a more specific, narrower meaning than tempo:

Other hyponyms of tempo include accelerando, allegretto, andante, meno mosso, rubato.

tempo (noun)	allegro (noun)
the rate of some repeating event	a musical composition or musical passage to be performed quickly in a brisk lively manner
(music) the speed at which a composition is to be played	a brisk and lively tempo

tempo (adjective)	allegro (adjective)
	(of tempo) fast

tempo (adverb)	allegro (adverb)
	in a quick and lively tempo