culmination vs ending

culmination and ending both are nouns.

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

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

Other hypernyms of culmination include conclusion, termination.

culmination (noun)	ending (noun)
a concluding action	the act of ending something
the decisive moment in a novel or play	the end of a word (a suffix or inflectional ending or final morpheme)
(astronomy) a heavenly body's highest celestial point above an observer's horizon	the last section of a communication
a final climactic stage	event whose occurrence ends something
	the point in time at which something ends