Physically Based shaders

Hi All

I'm new to Unity and wanted to ask what I imagine is a quick question. To set the context I am looking to implement a shader for clouds in the game.

So as I understand with Unity 5 came physically based shaders, what is the difference between the new PBS shaders and a shader like this from shadertoy (https://www.shadertoy.com/view/XslGRr)

Thanks.

Cheers

 

When people say "Physically Based Shading" they're usually referring to surface shading, like metal, concrete, wood, leather, etc. rather than volume shading and light scattering. Unity's default implementation doesn't even handle subsurface scattering like wax or skin (which Unreal Engine 4 does try to solve).

 

Thanks for clearing that up. My next question then is if I right click and create shader, would I still be selecting a standard surface shader for volume shading such as clouds?