At keystone the park is sort of in the upper middle part of the mountain. So from the gondola you have to ski down a little bit to the park (or you can take the peru lift straight to the top of it) After that, they have the A51 lift so pretty much all you can ski is park unless you want to ski down to the bottom (which is pretty far).
At breck they sort of have a park lift, lift 5. It was closed for like half the season last year though. It takes you from the base of peak 8 right to the top of park lane, the freeway entrance is skiers right about 500 feet. Without lift 5 you can take colorado or rocky mountain...colorado backs the fuck up though most days and rocky mountain requires you to traverse. Both lifts take you to the top and you have to ski down a little more than half the mountain to get to the park.
Breck's park last year was way more linear than keystone's. It was laid out more like jumps, rails, rails/jumps, rails, then rails/jumps. Keystone's park is wider, breck's is longer but narrower. Keystone has 4 separate park runs, all very different and they all dump into the same lift. Breck only has 2 park runs that dump into the same place (on peak 8 at least). Probably why I thought breck was more fun last year, but I'm sure someone will argue against that.