sound unit vs B

sound unit and B both are nouns.

Word	Noun	Adjective	Verb	Adverb
sound unit	Yes	No	No	No
B	Yes	No	No	No

As nouns, B is a hyponym of sound unit; that is, B is a word with a more specific, narrower meaning than sound unit:

Other hyponyms of sound unit include Bel, dB, decibel, sone, phon.

sound unit (noun)	B (noun)
any acoustic unit of measurement	aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil
	the blood group whose red cells carry the B antigen
	the 2nd letter of the Roman alphabet
	a logarithmic unit of sound intensity equal to 10 decibels
	a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder
	originally thought to be a single vitamin but now separated into several B vitamins