I am developing an engine that uses both OpenGL and OpenGL ES 2.0. I am well seasoned in OpenGL but not ES (although I am aware it is a subset of OpenGL). I could not find a set of differences that I should be aware of so that I can write code to take those differences into account and allow the engine to robustly handle the situation where a feature is not supported in OpenGL ES.
For example, the following forum post mentions a couple gotchas: http://forums.arm.com/index.php?/topic/13799-tips-tricks-opengl-vs-opengl-es/
A link to an exhaustive list would be nice.