Though both are synonyms of each other, there could be a slight difference between both in terms of meaning and application. Hijack usually means to illegally seize (an aircraft, ship, or vehicle) while in transit and force it to go to a different destination or use it for one's own purposes. Kidnap usually means to abduct (someone) and hold them captive, typically to obtain a ransom.

hahahaha what a intellectual question u can kidnap any person, and hijack is usually used for the airplane

kidnap = take a person hijack = take a plane