If you hunt then you are a hunter, some hunters may be more successful that others, if you go to the range and shoot guns but don't go out and hunt then you are a shooter. I used to go hunting with a rifle and kill (shoot) animals, some of which we ate, that makes me a hunter at the time, I have not hunted for around 6 years though and somewhat lost interest in hunting, but still enjoy the occasional shoot at a range.
To be a body builder or call yourself a body builder I believe you need to compete in bodybuilding, otherwise you are just a bloke training with weights (like myself), I been lifting weights since I was in year 10 at high school and I am nearly 50 now, never called or considered myself a body builder, as a matter of fact every time someone (friends/family/workmates etc) referred to what I do as body building I will correct them and say I am weight training.
Most people who train football will play in a game at what ever level it might be at some stage, so they may or may not refer to themselves as a foot ball player, but personally unless you been on stage you are not a body builder IMO.