Some people prefer CBR and some prefer POR. It depends upon what you are looking for in a resort. We have stayed at both and enjoyed both for different reasons.
Similarities:
Both resorts are very large and spread out.
Both have multiple bus stops that will take a few minutes for the bus to circumnavigate.
Both have a themed pool and multiple 'quiet' pools.
I recommend staying in a preferred location at both of these resorts.
Differences:
Pool is better at CBR for very young children, IMO.
'Tropical island' vs a 'southern charm' atmosphere, your pick which appeals more.
POR has a boat to DS - very nice.
Some fireworks are visible at certain spots around CBR.
POR has Yee Haa Bob entertainment.
POR has a nice horse and buggy ride available.
CBR has slightly larger rooms and most rooms are recently refurbished (all except pirate rooms, I believe).
CBR has pirate themed rooms - best avoided - they are distant, only have double beds and can be scary to some children!
POR has royal themed rooms - very nice but pricey for little extra real benefit (essentially just upgraded room decor).
Bus service really is quite variable and can be good or bad at any resort. It isn't predictably better at any resort, AFAIK, unless you are talking about one the the deluxe resorts within walking distance of a theme park. (If you can walk then that is a huge benefit. BUT No moderates offer that option.)
IMO, it is a worthwhile advantage to book a room in a preferred location at either of these large, spread out resorts.
Good luck choosing! Both are lovely resorts with a lot to offer. You should have a fabulous stay whichever you choose!