Hi, Jennifer!
What a fun dilemma!
The difference comes down to two major factors: size and theme/mood.
Disney's Port Orleans Riverside is a gorgeous, lush Resort, meant to evoke the beauty of the antebellum South. It is quiet and peaceful, with as many amenities as you might expect from a Moderate Resort: food court dining, a sit-down restaurant, shopping, pool and slide, etc. The rooms have recently undergone extensive refurbishment, and are really quite appealing.
And one special highlight at Riverside? The new Royal Rooms. Full of surprises and decor, if you can score one of these rooms for your visit, I would immediately release the other without further debate!
Disney's Caribbean Beach Resort is much larger than Riverside. Its theme is island-cool, with a fun tropical flair. Its room setups (minus the addition of the Royal Rooms) are like those at Riverside; it offers the same level of dining, pool, etc.
If you are looking for pure opinion, I would have to cast my vote for Port Orleans Riverside. Its rich landscaping and beautiful accommodations leave you feeling like you've stepped back in history. Peaceful and elegant, this Resort brings a sense of quiet to what can be a pretty hectic vacation.
But if you want to continue the vacation feeling, head toward Caribbean Beach. Boisterous and lively, the mood of this Resort is most certainly that of beachy fun.
So the choice, then, is yours to make. And isn't this a fantastic quandary to be in? Drop me a line; I would love to know what you decide.
Have a wonderful time!
See you later, celebrator,
-Deborah B.