intermixture vs combining

intermixture and combining both are nouns.

Word	Noun	Adjective	Verb	Adverb
intermixture	Yes	No	No	No
combining	Yes	No	No	No

As nouns, combining is a hypernym of intermixture; that is, combining is a word with a broader meaning than intermixture:

Other hypernyms of intermixture include combination, compounding.

intermixture (noun)	combining (noun)
the act of mixing together	the act of combining things to form a new whole
an additional ingredient that is added by mixing with the base	an occurrence that results in things being united
any foodstuff made by combining different ingredients