Road to 1000

Whats the difference between a 850 rated player and a 1000 rated player? And what training plan can I do to get there and beyond?

generally ive found that the biggest difference is their tactical awareness.  (spotting tactics for you and your opponent.) A really big part of is making one move blunders. 1000s make less of them than an 850 rated player. a way to start working on that is just making a "blunder check" just ask yourself if a piece can be captured, if you have some kind of tactic, etc. Also learn how to evaluate a position. Here is a video that i reccomend watching https://www.youtube.com/watch?v=3su1RGtmfcw

Improving Your Chess - Resources for Beginners and Beyond...

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

Almost nothing

So why isn’t every 1000 a 850 and vice versa?

They said almost

So like 1-2 less mistakes a game?

Tbh I don't think that there is a lot of differences between those two ratings. A way to improve your play would be to heavily invest in tactics puzzles: tactics are the #1 tool for winning a game.

Not necessarily. What I mean is that a difference of 150 points is not enough for there to be any noticeable differences between the two, especially not at that rating range. 

Great natural teacher. There's still some basic stuff he forgets to be explicit about, but if you listen there's a lot he does say overtly that many experts forget to make clear for beginners. He also has a basic endgames etc set of videos. One of the original youtube chess personalities, but superior to most. John Bartholomew. https://www.youtube.com/watch?v=U2huVf1l4UE

And the answer to the original question is indeed less hung pieces and complete miscalculations.