horseman vs equestrian

horseman and equestrian both are nouns.

Word	Noun	Adjective	Verb	Adverb
horseman	Yes	No	No	No
equestrian	Yes	Yes	No	No

As nouns, equestrian is a hypernym of horseman; that is, equestrian is a word with a broader meaning than horseman:

Other hypernyms of horseman include horseback rider, adult male, man.

horseman (noun)	equestrian (noun)
a person who breeds and cares for horses	a person skilled in equitation
a man skilled in equitation

horseman (adjective)	equestrian (adjective)
	of or relating to or featuring horseback riding
	of or relating to or composed of knights