A legal opinion is presented to a client and it presents both sides of a legal issue along with an opinion regarding the legal matter involved. A legal brief is filed with a court and provides only one side of the issue on behalf of the client's position. They both discuss the same law, just from different perspectives. Of course, I already stated this fact in my previous post, but you failed to acknowledge it.
Well, at least you have backed off from your earlier claim, which was utter nonsense:
That is exactly what lawyers do (exploring both sides of a legal issue and rendering an opinion), at least in the U.S.