highjacker vs road agent

highjacker and road agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
highjacker	Yes	No	No	No
road agent	Yes	No	No	No

As nouns, highjacker and road agent are synonyms defined as:

highjacker and road agent: a holdup man who stops a vehicle and steals from it

Other synonyms of highjacker include highwayman, hijacker.

highjacker (noun)	road agent (noun)
a holdup man who stops a vehicle and steals from it	a holdup man who stops a vehicle and steals from it
someone who uses force to take over a vehicle (especially an airplane) in order to reach an alternative destination