Press, not really close to the same thing. Proviron is used to block out the receptors so that the estrogen is not held in those cells. Its main use is an Anti-E substance, no real anabolic or androgenic properties there, esp at 50mg ed. Masteron on the other hand does not really convert to E, I will have to look back at that one, if my memory serves me right, I think its a DHT derivative, but dont hold me to it. Whatever the path it is from, it does not convert to E, and its a polisher substance, used Pre contest at lower BF, it will work like a Deca, but without any water retention, and it helps to bring out striations, and hardness. Proviron should be a staple in most cycles, but Masteron is best suited for Pre contest only, and works best in a stack. Alone, its pretty darn weak. Maybe Chris250 can chime in here with more info, to help you out. Good luck bro.
Big JC