RDem"Park" boots definitely have less forward lean than boots branded as race boots or any other kind of boots. However, you wouldn't want a completely neutral lean.
For people with "normal" biomechanics, you want to have at least 11° of forward lean to keep enough of your weight forward for proper balancing. At 10°, you have the feeling that you will fall backwards and it is difficult to properly balance.
12°-13° is considered very upright
14°-15° is considered relatively normal
16°-17° is considered to be aggressive
In our Atomic Hawx series of boots, for example, we have engineered a clever little piece on the boot that allows you to position your forward lean at 13° or 15° or 17°.
Your ideal forward lean has little to do with where you ski on the mountain and more to do with your biomechanics/ankle flexibility. Limitations in ankle flexibility will necessitate a boot with less forward lean. People without limitations can select what feels best to them. But to say that one is better for park or all mountain is not really accurate. For example, Keefer runs his Hawx 110 boots at 13° and Jossi runs his Redster Pro 130 boots at 17°. Both amazing park skiers, both in completely different boot set ups.