dirt bike vs motorcycle

dirt bike and motorcycle both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirt bike	Yes	No	No	No
motorcycle	Yes	No	Yes	No

As nouns, motorcycle is a hypernym of dirt bike; that is, motorcycle is a word with a broader meaning than dirt bike:

dirt bike: a lightweight motorcycle equipped with rugged tires and suspension; an off-road motorcycle designed for riding cross country or over unpaved ground
motorcycle: a motor vehicle with two wheels and a strong frame

Other hypernyms of dirt bike include bike.

dirt bike (noun)	motorcycle (noun)
a lightweight motorcycle equipped with rugged tires and suspension; an off-road motorcycle designed for riding cross country or over unpaved ground	a motor vehicle with two wheels and a strong frame

dirt bike (verb)	motorcycle (verb)
	ride a motorcycle