I've been doing some more research.
Basically the same, same genus, but two different species. The white tail tang is bright yellow as a juvenile, and then changes to that color pattern resembling a kole tang with a white tail. The white tail is the smallest tang, the max length recorded is 4.6"
That's a full inch less than an adult kole tang. They may be similar behaviorally, but I'm looking for the smallest tang period and still haven't decided if it will be okay to have but am looking into it