I am trying to understand the difference from a physical phenomena point of view, not just math. Surprisingly I think I got the cross product like in rotational momentum. You have the momentum vector and we have effective distance from the momentum vector R that needs to be perpendicular to the momentum vector. These two vectors produce a plane in which the best way to conventionally view angular momentum is a vector, L, perpendicular to this plane. I think I get this. Now work. So to have work, F and change in position, must be in line with each other, no plane. And it yields transfer of energy which physically has no direction, a scalar quantity. But can't we conventionally invent a vector as a product of F dot d? Btw, spinning a bicycle wheel and trying to change the axis if rotation makes me get a feel for the vector nature of angular momentum, and changing it. Thanks for any insight.