motortruck vs tow car

motortruck and tow car both are nouns.

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

As nouns, tow car is a hyponym of motortruck; that is, tow car is a word with a more specific, narrower meaning than motortruck:

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

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