The same, and then again, different.
I have found all of the rooms at the moderate resorts nearly identical. They are all about the same size, similar quality in build and finish. What you want to look at is location, and layout of the resort.
Coronado Springs was built as Disney's answer to a convention hotel. It is often full of business people there only to attend meetings. It has large meeting areas, and is designed to accomodate those visitors. It is very spread apart, and most amenities are not designed for the average traveler. One plus is that the pool is great, and never crowded. It is also out of the way unless you are headed for AK.
Carribean Beach is huge. It is nicely laid out, with seven (I believe) separate villages that have their own pool, etc... It isn't too far to walk to the main pool and restaurants from anywhere in the resort. It is also nicely located. Not far from Disney-MGM or EPCOT.
If you have the choice, I would lean toward staying at Port Orleans Riverside. Everything is close together, yet it is heavily wooded so it feels like you are isolated. The food court is great, as is the pool. Access is great to the parks and downtown Disney.
Good luck, I hope that helped!