truck vs motor vehicle

truck and motor vehicle both are nouns.

Word	Noun	Adjective	Verb	Adverb
truck	Yes	No	Yes	No
motor vehicle	Yes	No	No	No

As nouns, motor vehicle is a hypernym of truck; that is, motor vehicle is a word with a broader meaning than truck:

Other hypernyms of truck include automotive vehicle.

truck (noun)	motor vehicle (noun)
an automotive vehicle suitable for hauling	a self-propelled wheeled vehicle that does not run on rails
a handcart that has a frame with two low wheels and a ledge at the bottom and handles at the top; used to move crates or other heavy objects

truck (verb)	motor vehicle (verb)
convey (goods etc.) by truck