Via Gottfried Haider on GitHub.
The original Raspberry Pi contained an ARMv6 CPU, 256 or 512 MB RAM, and Broadcom VideoCore IV graphics. The Raspberry Pi 2 contains a quad-core ARMv7 CPU, 1 GB of RAM, and the same graphics as the original Pi.
Both primarily run a modified version of the Debian Linux distribution named Raspbian that was made to run on the ARMv6 CPU (and higher).
On the Pi 2 it is also possible to run other unmodified Linux distributions, such as Debian or Fedora, since those settled on the ARMv7 architecture as their “baseline” for modern ARM support. Yet on those distributions you might not have the necessary kernel modules and graphics library to make full use of the Pi’s peripherals. This page thus specifically talks about running Processing on Raspbian, on either the Pi or the Pi 2! (see also: General notes about running Processing on ARM)
Starting with Processing 3.0.1, releases are available on the download page. A full Raspbian image with Processing pre-installed is available here.
Each Friday is PiDay here at Adafruit! Be sure to check out our posts, tutorials and new Raspberry Pi related products. Adafruit has the largest and best selection of Raspberry Pi accessories and all the code & tutorials to get you up and running in no time!