I too had been on the lookout for some documents that pertained to the differences between Open GL 2.0 and Open GL ES 2.0. Since both of them are quite similar in function, I was wondering what made the Open GL ES 2.0 more preferable. Do you think it is because of additional options available?
If you compare the two specifications you will find that OpenGL ES 2.0 is much smaller than OpenGL 2.0. Fixed-function vertex and fragment operations have been eliminated and only programmable vertex and fragment shading is allowed.
Some other legacy functionality, such as direct mode rendering (i.e. passing one vertex at a time), line stippling as well as color index mode (i.e. rendering with a palette) were also removed.