In this sense - a 'fey-like' appearance would be some visual traits and aesthetics that make them appear touched by magic; things that would not be completely naturally occurring on their own, or believable without a high-magic setting to support them. Whimsy or dream-like can come into play, but, for a classification - Gnomes might be depicted with body styles and proportions that do not *quite* look like any naturally evolving mammal might end up at, and who do not *quite* look fully believable, without there being magic involved, as opposed to halflings, who should. Gnomes in our art representations from 5th all seem to have been given slightly over-exaggerated facial features, even in their most 'realistic' depictions, for example.
I was trying to get some good looks at gnome examples yesterday while I was getting my save files moved forward, but I'll have to wait on commenting for them fully until they're actually released to use as playable, anything before then would be premature, since they're obviously still being worked on. And I promised myself I'd try to look at dwarves along the way as well, and havne't gotten to that yet... and I promised myself I'd get around to doing full class-by-class break downs and analyses too, and haven't gotten to that yet either. I've got a lot still to do...
Today I was going to put together some analyses for certain encounters at a certain party... only to discover that they're all apparently broken right now and not displaying (I know Shadow and Astarion are in now, so they were the ones I planned for on the save file, but they aren't working now...), so I can't do the assessments. Instead, I'll get the branch save up to check on Minthara, which I believe is working fine still...