Your analysis is correct. It's also correct to say something like "The Rex Cube is a Master Skewb without corners.".
It's also correct to say something like "The Dino Cube is the puzzle made out of only the edges of a Rex Cube or Master Skewb.".
While there's no arguing that the solves are parallel in your comparisons, I would have to say the only "correct" answer comes from mechanism and intention, in which case the Re Cube is definitely just a curved cut Dino.