My friends who crossed the 2000 mark says what separates me from them is that they plan better. Many wins in the 1800 rating still relies on your opponent making a mistake, which is more likely to be in lower time controls so you might be able to get away with it in bullet. But in longer time controls, not knowing when to make a short term or long term plan is going to hold you down. I would say opening, end game, and tactics are all about the same, its just that 2000 plan better and can explain the idea behind their plan better.
We might be able to see the same plans as they do, but they will be better at recognizing which plan is the strongest for the position.
Plateau

I've been stuck at around 1850 blitz for the past 4 months or so and simply cannot break out of it, I had a short peak of 1925. What seperates an 1800-1900 from a 2000-2100 blitz? I have reached 2000 bullet and am starting to play some rapid as well (1500 currently)