I had both. They're the same thing BUT I had more problems with the shot. With the shot they reccomend you take calcium and folic acid supplements because it does something to your bones. I was 14 and was on it for 3 years and I had to drop out of PE class in highschool because I couldn't run, my hips hurt so bad. I got off it and it took 1 year to return to normal. Also had implanon after my daughter for 2 years I loved it! I was kind of heavy though, close to 200lbs so its not as effective. and my periods were regular and then irregular. usually they stop in smaller women though.