You have to be admitted to the bar to practice law. Which is to say, other lawyers must recognize you as a lawyer, and this recognition can be taken away.
More practically, this means (in America) that you need a JD degree (4 year grad school), to pass an exam, and pass a(n oftrn horrifically thorough) character background check.
There is a difference between “legal counsel” or “legal representative in court”, with the former being less restricted (“has a law degree” vs “attorney/has passed the bar exam”)
Because of that, I think you can practice law without being admitted to the bar. Chances are it varies by jurisdiction, though.