casting vote vs voting

casting vote and voting both are nouns.

Word	Noun	Adjective	Verb	Adverb
casting vote	Yes	No	No	No
voting	Yes	No	No	No

As nouns, voting is a hypernym of casting vote; that is, voting is a word with a broader meaning than casting vote:

casting vote: the deciding vote cast by the presiding officer to resolve a tie
voting: a choice that is made by counting the number of people in favor of each alternative

Other hypernyms of casting vote include ballot, balloting, vote.

casting vote (noun)	voting (noun)
the deciding vote cast by the presiding officer to resolve a tie	a choice that is made by counting the number of people in favor of each alternative