First, the P5100 is an upgrade from the P5000 by about 2MP, the P5100 has 12MP and with the new EXPEED chip can reach ISO 3200. There is also better 12-face face detection and a mode dial that has 15 presets. There is a flash hotshoe, and a 3.5x optical zoom lens with optical stabilization, and apparently there are adapter lenses for telephoto and wide-angle shots.
The Nokia P50 is dialed down a little bit from the P5100, it still does a decent 8.1 megapixels. The image stabilization is done electronically this time though. The improved face detections and the 15 preset mode dial are inherited though. It also receives a lens with a slightly longer focal length, it comes with a 3.6x zoom lens.
The P5100 will drop in September for $400. The P50 will drop in October for $230.
Nikon upgrades flagship COOLPIX P-series [via electronista]