200 looks more butch than the 197, although I think the 197 is nice and subtle and has its own appeal.
200 usually (always?) comes with the cup chassis, so better handling and the steering was revised and is quicker.
200 could be optioned with Recaros, where the 197 only had them in the R27 special edition
200 has 3 more hp, but I think a closer ratio gear box so feels a bit quicker; the 197 I drove felt slower than my 182 cup back to back
200 has the RS monitor (telemetry with g force readings, acceleration times and other silly things)
200 has bluetooth audio streaming as well as phone (not sure if the 197 has this)
200 is a four seater (no centre belt) where the 197 seats 5.
I may be wrong on a couple of details here, going from memory, but to me the 200 feels more focused.