Hi Melanie.
The Rainforest Cafe locations in Disney's Animal Kingdom Park and at Downtown Disney are pretty well the same, overall experience.
The Downtown Disney location recently underwent a bit of an 'expansion' on its exterior which now includes a fiery 'volcano.' This is interesting to look at while at Downtown Disney, however won't affect your dining experience inside the restaurant itself.
If you enjoy the Rainforest Cafe type of dining experience, I'd recommend that you also consider dining at T-REX, rather than at
both Rainforest locations.
T-REX features Dinosaur-themed dining amid prehistoric creatures and periodic meteor showers.
Personally, I've long preferred the Animal Kingdom location of
Rainforest Cafe as I find it to be a little bit less hectic at dinner time especially. Another nice feature about the Animal Kingdom location is that they serve breakfast there! It's another 'wild' way to start your Disney Day at Animal Kingdom Park!
I hope this information is helpful Melanie.
Wishing you a simply Magical time at Walt Disney World!
Kirsten