I'm 14, so I can't really lift a lot of weight, but my question is simple, for example on pushups you lift about 60% of your body weight in my case about 29 kilos (58 pounds), but trainers at the gym, say I can't lift more than 17 kilos (38 pounds) on machines and my question is:
Is there really a difference between machines and body weight?
Or could my maximum lifting weight be a little bit more, closer to what I lift with pushups?