When a singular character is selected, Illustrator shows Character Alternates menu (if one has the option enabled in Preferences > Type).

But while some glyphs look distinct enough, some are obscure.

These have names, Unicode codes (these are displayed in Glyphs)...
What’s good seeing three similar spaces? How can I choose properly from two similar looking small 'a'-s, as shown in the screenshot attached?
Why can’t I see what these character alternates are when I hover over them?