alternative vs deciding

alternative and deciding both are nouns.

Word	Noun	Adjective	Verb	Adverb
alternative	Yes	Yes	No	No
deciding	Yes	Yes	No	No

As nouns, deciding is a hypernym of alternative; that is, deciding is a word with a broader meaning than alternative:

Other hypernyms of alternative include decision making.

alternative (noun)	deciding (noun)
one of a number of things from which only one can be chosen	the cognitive process of reaching a decision

alternative (adjective)	deciding (adjective)
necessitating a choice between mutually exclusive possibilities	having the power or quality of deciding
serving or used in place of another
pertaining to unconventional choices