Essentially opposites. Test being approx 90% androgenic and 10% anabolic and Primmo being approx 90% anabolic and 10 % androgenic. mg per mg Primmo actualy builds more tissue over the long run but since test works faster, gives greater strength gains, increased agression, creatine synthesis and water retention and Primmo actually lowers e and burn fat, the overall opinion is that Primmo is a mild cutting drug and Test is a powerful bulking drug but that's mostly cosmetic. They both build muscle, Primmo just does it cleaner.