takeoff vs leaving

takeoff and leaving both are nouns.

Word	Noun	Adjective	Verb	Adverb
takeoff	Yes	No	No	No
leaving	Yes	No	No	No

As nouns, leaving is a hypernym of takeoff; that is, leaving is a word with a broader meaning than takeoff:

Other hypernyms of takeoff include departure, going, going away.

takeoff (noun)	leaving (noun)
a departure; especially of airplanes	the act of departing
humorous or satirical mimicry
a composition that imitates or misrepresents somebody's style, usually in a humorous way
the initial ascent of an airplane as it becomes airborne