tractor trailer vs truck

tractor trailer and truck both are nouns.

Word	Noun	Adjective	Verb	Adverb
tractor trailer	Yes	No	No	No
truck	Yes	No	Yes	No

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

Other hypernyms of tractor trailer include motortruck.

tractor trailer (noun)	truck (noun)
a truck consisting of a tractor and trailer together	an automotive vehicle suitable for hauling
	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

tractor trailer (verb)	truck (verb)
	convey (goods etc.) by truck