The R100 has a fixed LCD display and is not touch enabled.The R50 has a multi-angle LCD monitor that can be flipped to the side and rotated 180˚, it's also touch enabled.
The R100 can shoot 4k 24p with a 1.6x crop. There's a 29 minute 59 second record limit.The R50 can shoot 4k 30p with no crop. The record limit is 1 hour.