They might seem like both nodes output the same coordinates whereas in reality the "Geometry" node outputs world normals; and the "Texture" Coordinate outputs object normals. What they have in common is that they both output the outwards-direction on any given point on the surface of a mesh as a vector represented in RGB format, the difference between world and object normals being that object normals are relative to an object's coordinates and world normals align with the coordinates of the editor. You can see the effect by rotating an object while using these two different normal outputs as an emissive color.