what's the main difference between a 1300 and a 1800 player?

1300s think that they are underrated and are really aroung 1500.

1800s think that they are underrated and are really aroung 2000.

Ha, true.

On average 1800 players will be better at every aspect of chess than 1300 players.  However IMO the two biggest reasons why 1800s beat 1300s are:

1. 1800 players very rarely hang pieces either en prise or to simple combinations, whereas 1300s will usually do so at least once a game

2. 1300 players are prone to obvious positional errors like leaving weak squares because of rash pawn moves, which 1800s are aware of

Also tactics, endgame, and opening...

1800 players know more patterns they can use. They see more and are tactically sharper (blunder less, find more combinations ...).

But, of course, neither 1300 nor 1800 players are good chess players...   

                    I'm sure your a fine person Jenium but I have to protest your avatar. That Emu belongs to someone I know

You might be talking about my twin sister. We look very similar...

Lol  ^.

                   The Ooooold twin Emu trick   I should of known!   SORRY

-Tactics ( In the sense "aw crap, i missed that" )

-Board Vision ( in the sense "crap, that Fiachettoed bishop :(" )

-Middlegame plans ( in the sense that if nobody blundered a piece away i am like "wtf am i supose to do now?" )

I am saying this cause ia have a friend here in chess.com who happens to be my colleague at work and he's like 1800, and these are 3 areas in which he's way better than me. 

most people seem to get it.

1800's are not really that good its just they are not quite as bad as 1300's.

there is no checklist of items that will bring you from 1300 to 1800, you just have to understand the game a bit more.

Truth! I'm a patzer that knows a little bit on tactics and openings. 

right, there are so many mistakes to be made in chess. An 1800 makes them often. A 1300 even more often and adds obvious blunders to his play.

I wonder if there has been anything said in this thread that cannot be applied to the difference between a 2300 player and an 1800 player.

Consistency.

This is a common topic, and there are some good lists on what players at certain levels usually know: 

http://www.chess.com/article/view/0---2000-a-roadmap-of-chess-knowledge

Yeah, I remember that article. I know the guy is an FM, but that doesn't automatically mean he knows what is going on at the levels below him.  That list is full of crap. In general, highly overestimating what each group knows.

I found it spot on... yes there are some things that are overestimated, but others are underestimated as well. (I don't think 1400 players knows Philidor and Lucena positions for instance). But I think many 1500 players can checkmate with K+Q/R blindfolded.

His list is based on his students knowledge, and people who have a coach probably know more 'facts' about chess than the average player of the same level.

Being 1330 in january, and 1735 now gives me fresh experience from both perspectives. I am not 1800, but I do play like 1800 in my best games, and I also meet a lot of 1800 players.

Maybe because they are.

Players on the way up are always underrated.