departing vs outbound

departing and outbound both are adjectives.

Word	Noun	Adjective	Verb	Adverb
departing	No	Yes	No	No
outbound	No	Yes	No	No

As adjectives, departing and outbound are synonyms defined as:

Other synonyms of departing include outward-bound, outward.

departing (adjective)	outbound (adjective)
that is going out or leaving	that is going out or leaving