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

hic's posts were easily the most informative, except his first which was too cryptic, probably because it was off the cuff.

The way I see it, a 1300 has at best a clear vision only 2 moves (four plies) ahead in an unclear position where material is about equal, whereas an 1800 would see equally clearly 3 moves ahead.

Not much you may say, and it does not matter, EXCEPT when that extra move is seen every time the player moves.

I may be wrong in all that, and will accept correction from someone who actually knows what he, (for human being), is talking about.   

And that's one of the main reasons it's hard to improve as an adult - too many other responsibilities. I'm fortunate enough that I have extra time because of an extremely supportive spouse.

I breathe chess.

It's been about two years since I started taking chess seriously and I've only played about 50 serious games during that time - I study non-stop and stretch my mind through calculation exercises. I've improved by about a thousand points from when I started and I continue to get better every day.

Being able to see ahead is of little value unless you can evaluate the resultant position.

The main difference? One has an 8, one has a 3.

Both will be crushed by a super GM so you can argue there is no difference

1800 usually plays better

I agree - but if the moves are forced I can calculate much, much further than three moves.

Once I sac'd a rook for mate in seven (it was actually mate in five but I missed the simpler mate).

The more you play chess and stretch your mind, and the more you learn "shortcuts" - patterns, combinantions, etc - the further you will be able to calculate. It will become much easier.

The hard part is judging the position in your mind after calculating, because you have to notice all the nuances of the visualized position. After only three or four moves of calculation into a middlegame position, things become very foggy for myself, whereas IMs and GMs can go ten or even twelve moves deep in an unforced sequence of moves. If some of the moves are forcing, and it's an endgame - they can calculate indefinitely.

I have played some 1300s who can calculate a single line as well as a GM. They tend to fall apart tho when there are several lines to calculate.

One counter-intuitive point about calculation should be highlighted:

the stronger the player, the less they need to calculate! Quite often, GMs only calculate a few moves then make a judgment about the position. They can usually tell whether there's an attack in the position, or something else that needs to be calculated further. But in most positions, they have such a fine sense of position that they evaluate the positions better and more quickly than anyone else.

What this means for 13xx players is that they often spend a lot of time calculating variations that aren't critical to the position, and evaluating the lines they do calculate incorrectly.

1800 strength players are much better at recognizing forcing moves and usually have a better sense of what endgames are advantageous to them.

Even so, 1800s are still usually very weak in one or more critical areas. I've seen masters routinely reach equal or even inferior endgames against 18xx players, only to win easily. How many times have we seen posts by 18xx players saying they *nearly* beat a master and that the computer said they were winning, but they made just one mistake or ran out of time? From the master's perspective, the game is usually viewed as a fairly routine win?

SmyslovFan knows his Chess. I am sure he is right when he says that Calculation is not always necessary, which sort of contradicts the idea that Tactics are 99% of Chess. It goes by the name Intuition or Experience, which are both closely related to the ideas of Position and Evaluation.

But faulty Tactics/Calculation exact a heavy price and quickly. Faulty Intuition or Positional Sense result in a slow and painful loss.

500 points difference, as all the shallow wits have said, says it all. They are correct in a trivial way.

My own experience is that, faced by a player 250 points or more better than me, I am going to win very few games.

Faced by a player 500 points better, who takes the current game seriously, and I may as well regard playing on as a waste of time, unless I learn something, which is very seldom, as the point is too subtle.  

As a slightly humorous aside, I did beat a player rated over 2000 in a game not long ago. I could not believe his blunder into a very crude trap I set.  He was either drunk, or made a perfunctory move without thought. He wiped me off the board in the return game in very short order.

The trap I set was opportunistic, as I sought to get a position where I made a forced move, which whilst desperately needed for defence, also was a the trap.

His mistake was to immediately continue his plan, instead of swatting the fly away before smashing me. 

Cheapskate stuff but it made my Chess Year!

I understand the technical Chess Term is Swindle.

500 points

One is a sitting duck, and the other is a hunter!

The reason I chose the following games is because they are good illustrations of the typical way in which weaker players overextend their pieces, and the way they make judgments about a position....and how fast they can get blown off the board when they do.

I am by no means a strong player, but it's easy to see there is a big difference between a class A/B OTB player and a Class D player.

In the first game, it was a clear case of overextension, and in the second game, the weaker player judged that exposing my king would be good for him - all he could see was that my king would be robbed the right to castle. He completely missed everything else about the position. Such judgement are typical of weaker players:

Here's what a 500 point rating difference - overextension, blown off the board:

Against an 1500 - the theme is misjudgment:

I once analyzed a position with Peter Svidler. I recommended a move that stopped an apparent attack but weakened the kingside pawns. He said it was bad, so I asked why. He said, "it just is". I analyzed the position on my own afterwards, and found out he was right. It took me about an hour to come to the same conclusion he knew instantly. 

My view is based on my club mates and friends. In our club championship we have the  groups Master, 1,2 and 3. Group 3 is now ca below 1600 to unrated.  I have been in that group since 2014 and  can see improvement all over the group. Myself I have grown 300 Norwegian elo. Group 2 is ca 1600-1700 and group 1 is ca 1800. In those higher groups it looks like most adult players has stabilized on that level.   

Back to the mathematics. I feel that rating is like the water in the sea. It wants to level out. The average rating for active club players is maybe around 1700 Fide, which means that its natural to climb if you are below  and natural to stay there when you get there. Those who got there used to be below earlier. Think of the ladder: All that have climbed to level 1800 was on the way up when they passed 1300.

Draws 

Do you mean that 1800s are working for draw in bad positions, and the the 1300s go for the win anyway and therefore loses?   I think the 1300 usually win or lose, and  seldom saves a draw.

1300 vs 1800?

One loses immediately, the other has figured out how to prolong losing.

Draws can be an advantage to lower rated player gaining a few points instead of losing more. But as Bobby Fischer hated draws and played to win as do I. Discipline, patience and skill are main differences.

I once played a 1550 rated player (USCF) who absolutely CRUSHED me even though i had chances against him. I was rated 811 at the time.