compounding vs combining

compounding and combining both are nouns.

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

As nouns, compounding and combining are synonyms defined as:

compounding and combining: the act of combining things to form a new whole

Other synonyms of compounding include combination.

compounding (noun)	combining (noun)
the act of combining things to form a new whole	the act of combining things to form a new whole
	an occurrence that results in things being united