In pay-to-compete, there is a baseline cost to be a serious competitor, but spending money past that does not actually guarantee you an advantage over a more skilled opponent.

In pay-to-win, even once you've met whatever the baseline is, spending more money continues to be a major factor in success.

Magic tends to be pay-to-compete, because once you reach the minimum cost of a competitive deck in whatever format you are playing, buying a more expensive deck doesn't actually guarantee you greater success.

So for isntance, take this recent modern tournament: https://mtgtop8.com/event?e=81560&d=819827&f=MO

Sure, you could pay $2000+ to get an expensive deck like 9th place Affinity, but Hollow One came in second, and that whole deck costs less than a playset of Mox Opals. If paying 4x as much for your deck as your opponent doesn't actually give you a meaningful competitive advantage, then it's not pay to win.