standard and diffuse

Hello everyone,

I'm using blender2crystal and I've noticed that, when using certain renderloops, every mesh can be given three shaders instead of one. A standard shader, diffuse and ambient. I always set the ambient shader to the vacancy of ambient, because if this place is unoccupied the mesh seems to get all black. It doesn't seem to matter what's put there tough.
Diffuse is a big riddle to me, because according to wikipedia diffuse lighting of a surface is calculated by dotting the light unit vector with the surface normal unit vector. But assigning shaders to the diffuse vacancy doesn't seem to do anything.
Then there's the standard vacancy. Every shader that is put there works differently. But I've got no idea how that one calculates lighting.

What I would like to find is some page, explaining these things. Because on the blender2crystal site I can't really find complete information about this.

Thanks.