truck vs semi

truck and semi both are nouns.

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

As nouns, semi is a hyponym of truck; that is, semi is a word with a more specific, narrower meaning than truck:

truck (noun)	semi (noun)
an automotive vehicle suitable for hauling	a trailer having wheels only in the rear; the front is supported by the towing vehicle
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	a truck consisting of a tractor and trailer together
	one of the two competitions in the next to the last round of an elimination tournament

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