What's the difference between Sample and tex2D I am mainly using Unity but I think that it's not related to this engine, and I am wondering what's the difference between using tex2D and Sample for sampling a texture.
They represent the same operation, but Sample is what it's called in D3D10 and newer versions of HLSL, while tex2D is what it's called in D3D9 HLSL, and NVIDIA's (defunct) Cg language. By the way, the operation is also called texture in GLSL.