#racial implications

Tokenism is defined as "the practice of making only a perfunctory or symbolic effort to do a particular thing, especially by recruiting a small number of people from underrepresented groups in order to give the appearance of sexual or racial equality within a workforce."

the difference I would say is the approach and way that the author frames the character(s)

a background character withi vitiligo is a person who exists and happens to have vitiligo

a token character is a background character that exists fully for the intent of showcasing that there is a disabled character at least somewhere in the story even if they're there for a split second.

With vitiligo tokenism could also play a role in colorism as well as its a disorder involving pigmentation loss. So a token character of color might have vitiligo to subconsciously make them whiter.

LMAO

I think it has to do more with the aesthetic-fication of it than the actual rarity itself. There's also a lot of other factors that could go into it, mainly things like how colorism can change the way people want to depict certain characters; like how vitiligo has a tendency to be used as an excuse to white-wash. It also gets treated like it's a more "palatable" disability compared to a lot of other ones, so it makes it easy for people to go "hey look! I have a disabled character!" without the need to actually do any research or anything.