Möchte - Freundlich, nicht so stark. Will - Starker Ausdruck, unbedingt. The difference is about if you really want something badly or if you just humbly ask for something. For instance: Ich möchte ein Eis -> I would like Ich will -> I want In English there might not be a difference but here we actually do care about it. So if you say "Ich will" it will show others your strong desire to do it or for something. So you have to know for yourself which one fits for your case.