carjacking vs highjack

carjacking and highjack both are nouns.

Word	Noun	Adjective	Verb	Adverb
carjacking	Yes	No	No	No
highjack	Yes	No	Yes	No

As nouns, highjack is a hypernym of carjacking; that is, highjack is a word with a broader meaning than carjacking:

carjacking: the violent theft of an occupied car
highjack: seizure of a vehicle in transit either to rob it or divert it to an alternate destination

Other hypernyms of carjacking include hijack.

carjacking (noun)	highjack (noun)
the violent theft of an occupied car	seizure of a vehicle in transit either to rob it or divert it to an alternate destination

carjacking (verb)	highjack (verb)
	take arbitrarily or by force