I have a png that I was using as a sprite, but now I want to use it as a texture. So when doing Resource.Load(...), what would I load it as? A Texture2D or a Texture?
Texture2D. Texture is the base class from which Texture2D, Texture2DArray (5.4), Cubemap, etc. (different types of textures) inherit from. You're loading in a sprite, which is a 2D texture.