Fuji released its XPro1 way back in 2012, and since then the camera has recieved many firmware updates from Fuji, improving the performance and utility. As with any camera, technology improves and Fujifilm has embodied many improvements in the new XPro2 but keeping the camera size and shape and OVF/EVF functions in the same vein as the original.
XPro1: http://www.dpreview.com/reviews/fujifilm-x-pro1
XPro2: http://www.dpreview.com/reviews/retro-t ... ons-review
Here is a comparison site between the two cameras: http://www.fujivsfuji.com/fuji-xpro2-vs-xpro1/
Core differences are significant as we might expect. The new camera has major improvements:
Weatherproofing,
24Mp Sensor
273 focus points (77 on XPro1)
Dioptre adjustment (required eyepiece lens changes on XP1)
Higher res display and VF.
Dual SD Card slots.
Faster processor.
Also in the pipeline is the X-T2 to replace the X-T1, probably to pick up many of these improvements. Due in the second half of 2016.