The naming of these two nodes is a bit inconvenient, I think…It took me a few years before I understood the difference and when to use which, (This was before the different types of Nodes had different colors; all the Nodes where grey, which made it a lot less obvious…I can’t even look at that any more.)
A Mix Shader is not just a ‘Shader that mixes’, but it mixes Shaders. In the same way: a Mix RGB, mixes (RGB) colors.
I like to think of them as ‘Shader Mixer’ and ‘RGB Mixer’…
Also an Add Shader is not just a ‘Shader that adds’, but it adds Shaders together, so more of a ‘Shader Adder”…
