https://forum.unity.com/threads/how-to-sample-a-texture-in-vertex-shader.513816/
GreatWall said: ↑
So "mip mapping" and "level of detail of a texture " are different? I always confused about these terms.
LOD controls which mip-map is used. As he stated, the automated value for choosing which mip-map level to use isn't know till fragment stage. Thus, you use the tex2Dlod method because it requires you state a specific mip-map level to sample from.