First up, it is possible to say that compound interest earns more money that simple interest if we are taking the moneylender position, other case is a loss for the payer.
It is possible to say that compound interest earns more money because for taking into account the amound of money to be paid the future interests are added to the original debt. So that, the interests are paid not only over the original amount of money that was asked, but also are they over the interests that this money is going to generate in certain period of time.
In contrast, in simple interest, these are paid only over the original amount of money, without taking in consideration future debts.