More memory, more resolution.
Mark Cerny, lead system architect at Sony, has revealed in an interview with Eurogamer that the PS4 Pro will feature an extra gigabyte of RAM. While the standard PS4 comes with 8 gigabytes of GDDR5 RAM, the extra GB added to the PS4 Pro will be slower DRAM of the DDR3 variant.
According to Cerny, the idea here is to off-load applications to the slower RAM when they are not in use, freeing up “almost one gigabyte of the eight gigabytes of GDDR5”. Of this freed gigabyte, half is dedicated to the PS4 Pro interface, which will now be rendered in 4K resolution. The remaining half gigabyte, of course, goes to the actual game that you are playing.
The PS4 Pro is a more powerful variant of the PS4, and features 4K rendering for games, as well as improved quality for PlayStation VR. Despite the extra performance, the PS4 Pro will share its library with other PS4 variants.