hijacker vs road agent

hijacker and road agent both are nouns.

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

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

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

Other synonyms of hijacker include highjacker, highwayman.

hijacker (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