wildcatter vs oilman

wildcatter and oilman both are nouns.

Word	Noun	Adjective	Verb	Adverb
wildcatter	Yes	No	No	No
oilman	Yes	No	No	No

As nouns, oilman is a hypernym of wildcatter; that is, oilman is a word with a broader meaning than wildcatter:

wildcatter: an oilman who drills exploratory wells in territory not known to be an oil field
oilman: a person who owns or operates oil wells

wildcatter (noun)	oilman (noun)
an oilman who drills exploratory wells in territory not known to be an oil field	a worker who produces or sells petroleum
	a person who owns or operates oil wells