No.  Just means that, in the eyes of the law, freeze brands aren't recognized as legal marks of ownership on livestock.

A perfect freeze brand will leave little to no hide scar(only permanent damage is to the hair folicle itself), whereas the hot iron brand is a legible scar on the hide. 

An imperfect freeze brand can leave a very noticeable hide scar with white hair growing around it, or it can be just a few white hairs, big range for errors.  And possibly the freeze brand can be 'hidden' with dyes, paint, etc. to temporarily skirt ownership claims.