The two games are extremely different. JD is a strategic mainly mode-based game that requires accurate shooting. I suggest setting it up super difficult for the best enjoyment out of it.
The Getaway is a sequel to High Speed and retains a lot of the simplicity of the rules of the original, while adding some unique toys. Personally, I don't like the toys at all, and perhaps because of that, I have never been too personally enthralled with it.
I'm happy to play the Getaway on route when I see it. I have never wanted to own one. JD has been a keeper for 10+ years.