user18674: I'm a casual player who enjoys playing the King's Indian Defense as Black, but I don't fully understand yet when it is better to play 6...e5 or 6...c5. These are my main doubts:

What are the aims and differences about playing one move instead of the other?
In which conditions (such as position of opponent's pieces) should I play 6...c5 instead of the more characteristic 6...e5?

I've looked at this very interesting question about the aims of playing 6...e5, but it does not mention anything about the difference between the two aforementioned moves.
Any extra insight or suggestion is of course more than welcome!

user7726: I'm not a KID expert, but Joe Gallagher GM is, so I'll quote him from "Starting out: The King's Indian":

"If you are going to play the King's Indian with Black you may be a
  little confused as to whether you should aim for ... c7-c5 or ...
  e7-e5. I tend to adhere to the following rule:
Play ... e7-e5 except when White develops his queen bishop early. Then
  it's time to start thinking (just thinking mind you) about ... c7-c5.
  The move ... c7-c5 is likely to prise open the long diagonal (after
  ... e7-e5 it usually becomes totally blocked) and the absence of the
  white bishop from the queenside means the dark squares there (such as
  b2) may become vulnerable to pressure from the g7 bishop"


18674: <p>I'm a casual player who enjoys playing the King's Indian Defense as Black, but I don't fully understand yet when it is better to play <code>6...e5</code> or <code>6...c5</code>. These are my main doubts:</p>

<ul>
<li>What are the aims and differences about playing one move instead of the other?</li>
<li>In which conditions (such as position of opponent's pieces) should I play <code>6...c5</code> instead of the more characteristic <code>6...e5</code>?</li>
</ul>

<p>I've looked at this very interesting <a href="https://chess.stackexchange.com/questions/16167/why-6-e5-in-kings-indian">question</a> about the aims of playing <code>6...e5</code>, but it does not mention anything about the difference between the two aforementioned moves.</p>

<p>Any extra insight or suggestion is of course more than welcome!</p>
 7726: <p>I'm not a KID expert, but Joe Gallagher GM is, so I'll quote him from "Starting out: The King's Indian":</p>

<blockquote>
  <p>"If you are going to play the King's Indian with Black you may be a
  little confused as to whether you should aim for ... c7-c5 or ...
  e7-e5. I tend to adhere to the following rule:</p>
  
  <p>Play ... e7-e5 except when White develops his queen bishop early. Then
  it's time to start thinking (just thinking mind you) about ... c7-c5.
  The move ... c7-c5 is likely to prise open the long diagonal (after
  ... e7-e5 it usually becomes totally blocked) and the absence of the
  white bishop from the queenside means the dark squares there (such as
  b2) may become vulnerable to pressure from the g7 bishop"</p>
</blockquote>
