ummm well, I'm going to have to go with Peltra on this one...

Materials are blinn, lambert, phong, etc, while a shader is the material, color, bump map should there be one, extra nodes you create in hypershade to make up the network if you do that, etc, all put together.

What's a material in real life? Silk, cotton, concrete, plastic, etc. They all have a different feel to them and light reflects diffrently off them. Maya can simulate different materials of real life with the different materials like blinn, lambert, etc that it has.

Now silk, cotton, concrete, etc will always have the same characteristics, but their color can differ. Even though concrete is concrete, you can have relatively smooth concrete or rough concrete. A bump map would be able to simulate this. Bump maps are considered to be part of a shader, not a material.

hope this better explains it all somewhat...