Too many times I have been in my car on the parkway trying to reach my destination when I have encountered situations like in the picture below. Do those cars appear to be driving or parking. That's right, these cars are basically 'parked' on the parkway. No, they have not switched the gear shift to P, but sitting with your foot on the brake produces the same response.
Now I ask you, how many times have you encountered traffic or a situation when you were forced to sit 'parked' in your driveway? Every time I enter my car on my driveway, it is smooth sailing. I can drive as slow or as fast as I please down it until I reach the street.
In conclusion, the two are aptly named. We do drive on the driveway and park on the parkway. Enjoy your driving, or rather, parking!