withdrawal vs leaving

withdrawal and leaving both are nouns.

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

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

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

withdrawal (noun)	leaving (noun)
the act of withdrawing	the act of departing
formal separation from an alliance or federation
the termination of drug taking
the act of taking out money or other capital
a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation
the act of withdrawing blood, tumors, etc.
the act of ceasing to participate in an activity
a retraction of a previously held position
avoiding emotional involvement