woofer vs speaker unit

woofer and speaker unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
woofer	Yes	No	No	No
speaker unit	Yes	No	No	No

As nouns, speaker unit is a hypernym of woofer; that is, speaker unit is a word with a broader meaning than woofer:

woofer: a loudspeaker that reproduces lower audio frequency sounds
speaker unit: electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance

Other hypernyms of woofer include loudspeaker, loudspeaker system, speaker, speaker system.

woofer (noun)	speaker unit (noun)
a loudspeaker that reproduces lower audio frequency sounds	electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance