What's the difference between 2 options “ignore for this font” or “ok” when opening?

When you open a .glyphs file saved in a different version of the app, it gives you 2 options, “ignore for this font” or “ok”. What’s the difference? What exactly is done for either option?

Ok just dismisses the dialog. So if there will be another version change in the future, it will show up again. Ignore should silence the dialog altogether.