determining vs determinative

determining is not a noun while determinative is a noun.

Word	Noun	Adjective	Verb	Adverb
determining	No	Yes	No	No
determinative	Yes	Yes	No	No

As adjectives, determining and determinative are synonyms defined as:

Other synonyms of determining include deciding, determinant.

determining (noun)	determinative (noun)
	a determining or causal element or factor
	one of a limited class of noun modifiers that determine the referents of noun phrases

determining (adjective)	determinative (adjective)
having the power or quality of deciding	having the power or quality of deciding