I have to learn open GL and get a basic open GL app built. Is it easier to learn open GL 1.x ES as apposed to 2.0 which uses shader language? Also is it advisable to learn 1.x before 2.0?
As already mentioned OpenGL 1.x and 2.x are very different.
OpenGL ES 1.0 uses a fixed pipeline, which is a fancy way of saying you use built-in functions to set lights, vertexes, colors, cameras, and more.
OpenGL ES 2.0 uses a programmable pipeline, which is a fancy way of saying all those built-in functions go away, and you have to write everything yourself.
To get more info on topic with good tutorials, check resources listed below
OpenGL ES 2.0 can be hard to understand coming from 1.1 especially if one was using the fixed pipeline as a black box.
In 2.0 you write programs in a C-like language called GLSL that are executed in the graphics card for each vertex or fragment.
For 2.0 you do absolutely need to know your vectors from your matrixes in order to do anything.
I'd recommend using the 1.1 manuals for reference if anything to get all the basic useful matrixes and then using 2.0 as fixed pipelines are just not coming back anytime soon.
GLSL is easy and once you have emulated the old fixed pipeline you can extend it to do things like cel-shading or reflections.