conjugation vs combining

conjugation and combining both are nouns.

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

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

Other hypernyms of conjugation include combination, compounding.

conjugation (noun)	combining (noun)
the act of pairing a male and female for reproductive purposes	the act of combining things to form a new whole
the act of making or becoming a single unit	an occurrence that results in things being united
a class of verbs having the same inflectional forms
the complete set of inflected forms of a verb
the inflection of verbs
the state of being joined together