Depends on how you mean. Sarah hasn't earned her living as a dancer since she was in her twenties, I think. Thirties at the latest. Obviously, she'll still have the innate talent but she's not been dancing for at least twenty years, possibly close to thirty years.
Tasha is a professional dancer. That's how she was earning her living until Love Island and it may still be her noted profession.
It's not fair to say that she's no different than Sarah because they obviously are very different. Not all ringers are equal. Tasha is pretty much up there with the ringiest of ringers. I'm not keen on that level of ringer but accept that others don't mind at all.