groom vs hired man

groom and hired man both are nouns.

Word	Noun	Adjective	Verb	Adverb
groom	Yes	No	Yes	No
hired man	Yes	No	No	No

As nouns, hired man is a hypernym of groom; that is, hired man is a word with a broader meaning than groom:

Other hypernyms of groom include hand, hired hand.

groom (noun)	hired man (noun)
a man who has recently been married	a hired laborer on a farm or ranch
someone employed in a stable to take care of the horses
a man participant in his own marriage ceremony

groom (verb)	hired man (verb)
care for one's external appearance
give a neat appearance to
educate for a future role or function