tow truck vs motortruck

tow truck and motortruck both are nouns.

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

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

tow truck: 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 truck include truck.

tow truck (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