The difference between a higher rated player and a lower rated one is that the higher rated player does everything slightly to a lot better.
If you're able to attribute certain actions to higher rated players you already do them you're just worse at them.
Yes, pretty much this. When I was active I peaked at about level 60 and I certainly didn't "plan for turn 7 on turn 1". Right now I'm about level 55 and I'd describe it as
Under 50: what are you even doing
50-53: you kinda get what's going on here, but you make big blunders that don't get punished at your level
53-55: you usually get a strategy that's reasonable but may miss a better one, and also still make big blunders
55-60: you get what's going on but still make lots of small mistakes, and one or two huge ones
60 and up: you get what's going on and make fewer small mistakes, but you still make plenty of them and the space of potential mistakes is much bigger at your level.
Based on watching streams, people in the level 54-58 see almost all the same strategies top players do, they're just worse at executing them in every way possible.
Generally the consistently-better wins come from better shuffle management early, better endgame play late, and better buy decisions for everything in between. The buy decisions are the biggest factor but it's hard to make general statements about this. The shuffles can be summed up as "have you thought about whether you want to trigger this shuffle", and the endgame can be summed up as "have you thought about 3-piles and what buys are safe and unsafe given your opponent's potential".