The difference between Vanilla and Glitchless is that in Vanilla, animation canceling is not allowed, while it is allowed in Glitchless. Any Vanilla run will, by definition, also meet the criteria for a Glitchless run, but the reverse is not necessarily true.

My understanding is that it is not possible to use animation canceling on Android. That means any Android run should be submitted as Vanilla. In many categories, the time difference between Vanilla and Glitchless is minimal, but in other categories, the difference can be rather stark (especially some of the new meme categories).