windup vs ending

windup and ending both are nouns.

Word	Noun	Adjective	Verb	Adverb
windup	Yes	Yes	No	No
ending	Yes	No	No	No

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

Other hypernyms of windup include conclusion, termination.

windup (noun)	ending (noun)
a concluding action	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

windup (adjective)	ending (adjective)
operated by a mechanism