truck vs motortruck

truck and motortruck both are nouns.

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

As nouns, truck and motortruck are synonyms defined as:

truck (noun)	motortruck (noun)
an automotive vehicle suitable for hauling	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

truck (verb)	motortruck (verb)
convey (goods etc.) by truck