withdrawal vs defection

withdrawal and defection both are nouns.

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

As nouns, defection is a hyponym of withdrawal; that is, defection is a word with a more specific, narrower meaning than withdrawal:

withdrawal (noun)	defection (noun)
the act of withdrawing	withdrawing support or help despite allegiance or responsibility
formal separation from an alliance or federation	the state of having rejected your religious beliefs for your political party or a cause (often in favor of opposing beliefs or causes)
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a method of birth control in which coitus is initiated but the penis is deliberately withdrawn before ejaculation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