highjacking vs robbery

highjacking and robbery both are nouns.

Word	Noun	Adjective	Verb	Adverb
highjacking	Yes	No	No	No
robbery	Yes	No	No	No

As nouns, robbery is a hypernym of highjacking; that is, robbery is a word with a broader meaning than highjacking:

highjacking: robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force
robbery: larceny by threat of violence

highjacking (noun)	robbery (noun)
robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force	larceny by threat of violence
	plundering during riots or in wartime