tow car vs motortruck

tow car and motortruck both are nouns.

Word	Noun	Adjective	Verb	Adverb
tow car	Yes	No	No	No
motortruck	Yes	No	No	No

As nouns, motortruck is a hypernym of tow car; that is, motortruck is a word with a broader meaning than tow car:

tow car: a truck equipped to hoist and pull wrecked cars (or to remove cars from no-parking zones)
motortruck: an automotive vehicle suitable for hauling

Other hypernyms of tow car include truck.

tow car (noun)	motortruck (noun)
a truck equipped to hoist and pull wrecked cars (or to remove cars from no-parking zones)	an automotive vehicle suitable for hauling