Based on the video samples they look totally different, with the 2.4MP looking so much better, and with much better colors. White housing would be a nice option for outside walls and even inside stores. Black is useful for warehouses, night clubs, etc. Though when you bring out the Dahua 2.4MP AF Eyeball style dome, wont need this in white 
Also, while on topic I have some 2.4MP Dahua Auto Focus domes, and I just noticed what seems to be a design issue - a subtle bar that very slowly moves up and down the image. In fact you really cannot see it with the video, if you save a snapshot then save another 1 minute later (or longer) and flip between those 2 images, you should see this. It can be at the bottom, top, anywhere in the image.
I have gone back and saved snapshots from previous installs and low and behold, the same issue. It does not affect the other HD CVI cameras I have at the locations, and even which were on the same wire before swapping to the AF dome - eg. I first had a Manual Focus Varifocal dome, then replaced it with the AF dome.
I can send you a webpage to check out which shows this moving bar/lines.
I'm going to bring one of the cameras home tomorrow with a CVI DVR and troubleshoot it, see if I can find out the cause. It might be some hum from the motorized lens even. I have these AF domes powered on both individually fused PSU and PTC breaker PSU, so that counts those out.