Whats the difference between Mouse.Hit & Mouse.Target?

mouse.Hit refers to the position that the mouse was touching. mouse.Target refers to the part that the mouse was hovering on.

While for many things mouse.Target.Position will be pretty close to mouse.Hit.p they are not the same position (for instance, on a baseplate, which is large, so its center is far from points on its surface).

If you are looking for the position of the mouse in the world, use mouse.Hit. If you care about what they are hovering over, use mouse.Target.