The biggest benefit is you’ll only have to carry one device since the remote controller and display are combined. That’ll reduce the setup time too since you won’t have to mount the display and you’ll only have to power on one device.
Screen-wise, they will be comparable if you’re considering the 5.5" High Brightness CrystalSky. If you get the 7.85" Ultra Brightness CrystalSky, you’d have a larger screen and a display that’s double the brightness (2,000 nits vs. 1,000 nits) of the High Brightness CrystalSky and DJI Smart Controller. Most people have no trouble using 1,000 nit displays, so it’s probably not going to be a deal breaker if you don’t have the 2,000 nit display.