graduation vs culmination

graduation and culmination both are nouns.

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

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

Other hypernyms of graduation include closing, completion, mop up, windup.

graduation (noun)	culmination (noun)
the act of arranging in grades	a concluding action
the successful completion of a program of study	the decisive moment in a novel or play
a line (as on a vessel or ruler) that marks a measurement	(astronomy) a heavenly body's highest celestial point above an observer's horizon
an academic exercise in which diplomas are conferred	a final climactic stage