Hm, for me personally:
"pay-to-win" - you pay in order to increase your chances of winning, not mattering what your skill level is
"invest-to-win" - you invest in the gear necessary to compete on the level you want to compete in. Once you have reached that investment, you can't pay more to win more easily.
I know, it's just a slight difference and there is no 100% line in between those things.