He displays a planetary command of the Force (I will go into more detail if you wish) with just two years of training; he has since grown in power for a further ten years (5 times his then total amount of training), and given his abnormally large learning rate, instinctive link to the dark side, Force potential, and the general manner in which the dark side works, and it's pretty clear that as of his current peak he's vastly more powerful.