ascending vs ascension

ascending and ascension both are nouns.

Word	Noun	Adjective	Verb	Adverb
ascending	Yes	Yes	No	No
ascension	Yes	No	No	No

As nouns, ascending and ascension are synonyms defined as:

ascending and ascension: the act of changing location in an upward direction

Other synonyms of ascending include ascent, rise.

ascending (noun)	ascension (noun)
the act of changing location in an upward direction	the act of changing location in an upward direction
	a movement upward; rise above the ground
	(astronomy) the rising of a star above the horizon

ascending (adjective)	ascension (adjective)
moving or going or growing upward