beats per minute vs tempo

beats per minute and tempo both are nouns.

Word	Noun	Adjective	Verb	Adverb
beats per minute	Yes	No	No	No
tempo	Yes	No	No	No

As nouns, tempo is a hypernym of beats per minute; that is, tempo is a word with a broader meaning than beats per minute:

beats per minute: the pace of music measured by the number of beats occurring in 60 seconds
tempo: the rate of some repeating event

Other hypernyms of beats per minute include pace.

beats per minute (noun)	tempo (noun)
the pace of music measured by the number of beats occurring in 60 seconds	the rate of some repeating event
	(music) the speed at which a composition is to be played