Both decision and resolution words refer to the final statement made in connection with an issue. But they are used in different contexts.
In legal context, decision refers to both administrative and judicial determinations, for example, final judgments, rulings or provisional orders made by court. It also means a conclusion or a judgment reached after consideration or the act of making up one’s mind.
As for resolution, in legal sense, it means the official expression of the opinion or will of a legislative body but it can also refer to the determination of a policy of a corporation. Resolution is typically used in corporate decision making. Resolutions are arrived at after a voting process. It indicates that a problem is finally solved, it is a firm determination, or a formal statement of a decision.