embarkation vs leaving

embarkation and leaving both are nouns.

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

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

embarkation: the act of passengers and crew getting aboard a ship or aircraft
leaving: the act of departing

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

embarkation (noun)	leaving (noun)
the act of passengers and crew getting aboard a ship or aircraft	the act of departing