drug withdrawal vs ending

drug withdrawal and ending both are nouns.

Word	Noun	Adjective	Verb	Adverb
drug withdrawal	Yes	No	No	No
ending	Yes	No	No	No

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

Other hypernyms of drug withdrawal include conclusion, termination.

drug withdrawal (noun)	ending (noun)
the termination of drug taking	the act of ending something
	the end of a word (a suffix or inflectional ending or final morpheme)
	the last section of a communication
	event whose occurrence ends something
	the point in time at which something ends