Quality is the same. It’s just a different type of compression.
If you’re wanting to use a high bit rate with your 4K recordings you’re going to have to use a 3rd party app. FiLmIcpro is probably the best and it even lets you record in flat gamma and log gamma. Everything, and I mean everything, is totally adjustable from frame rate, bit rate, shutter speed, iso, WB, focus, zoom push and pull (setting the push and pull points and the zoom speed), same for focus push and pull, recording aspect ratio, etc.