Is there an absolute distinct difference between the Walker and the Popper. I've seen both.I think the shape of the body might be a little different and the sizes a little different.

Both the walker and the popper feature the same mouth and slits to create bubbles

Could the weight and positioning of the weight internally make any difference?

Because the WALKER has the same mouth features as the POPPER, couldn't the WALKER be used as a straight POPPER without imparting the walking action?

The mouth cups are shaped different. Look a little closer and you will see the walker extends further on the top, to where the popper is more level.