Aspect Ratio vs Fixed Resolution

So, under the game view’s tab, you can create your own screen size i suppose. What is the difference between Aspect Ratio and Fixed Resolution? Where should I use ratio and where should I use resolution?

I think this is the editor view that you talk about.

But for the game build exe there’s other option to set the screen resolution.

That depend of your need, if you want to have the same aspect ratio in editor
and built exe or if you don’t need it. If you have a non-scrolling game and
want to see if every object is on the screen …