Yes organic milk is RBGH free since organic milk comes from cows that are organically fed and not given any extra hormones.
All milk comes from cows including the organic milk but the difference is in the way the cows were raised and fed and cows that produce organic milk are fed natural grains and grass and not given any hormones or any non natural foods.
Organic milk is usually much healthier and even tastier than non organic milk is.
The BGH or RBGH treatment is a synthetic chemical called recombinant BGH which organic milk cows are not treated with.
So that makes organic milk healthier and RBGH free.