I have no idea about how big difference it is. But i have one token buying friend who's lvl 13. And he has 8 and 9 star quality players against my 5 and 6 stars. We played 2 games - one when he was home team and one when I was at home. I lost both games with only 2-0. So it can't be super big difference eventough i clearly lost. I was expecting a 15-0 or something. And I'm just lvl 2.