hijacking vs highjacking

hijacking and highjacking both are nouns.

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

As nouns, hijacking and highjacking are synonyms defined as:

hijacking and highjacking: robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force

hijacking (noun)	highjacking (noun)
robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force	robbery of a traveller or vehicle in transit or seizing control of a vehicle by the use of force