Decider means decider, and decision means determination, decision, resolution, decisiveness, judgment, etc. Decide common usage:

1.decision means "decide" and "solve", which means to solve a prominent problem. Its scope of use is very narrow, generally followed by questions, cases, arguments, disputes, results, competitions, fate and so on.

2.decideonsb/sth means "choice" and "decision", which means to choose one from several things or people, and it is widely used. One-stop study abroad strategy in ing.com