LogFAQs > #970472536

Overpowered just means something is too good. It can be because the backing numbers are too good. It can also be because the concept itself is fundimentally too good.

I feel like overtuned also just means too good but haven't seen it used often enough to be certain about the nuances. When someone says overtuned, I sort of picture a fighting game character whose moves are too fast, too safe and do too much damage. So perhaps it is a bit more focused on parameters.