It's the cameras that have seemingly seen the biggest upgrade - the rear shooter has grown in resolution from 5 MP to 8 MP, and the selfie cam at the front went from 2 MP to 5 MP. While the J3 2016 comes with 1.5 GB of RAM, on the J3 Pro we have a nice round 2 GB number. The 8 GB internal storage capacity is now doubled to 16 GB from the get-go, while the phone retains the microSD slot for its expansion.
Other than that, most everything else has stayed the same - the 5" Super AMOLED HD display, 1.2 GHz Snapdragon 410 chipset, and 4G connectivity with dual SIM capabilities. Unfortunately, that goes for the operating system version, too, as it has stayed Android 5.1 Lollipop, which, six months after the unveiling of its predecessor, is a pity no matter how you slice it.