If you are really interested in animals (as I am), I think you would enjoy both. I took the Backstage Safari about a year and a half ago. The guides describe alot about the care, feeding, behavior enhancement and housing for the animals. You do get to meet an animal or two (when I took the tour it was a giraffe and a bird, not it sounds like rhinos), but the tour is primarily educational.
I took the Sunrise Safari this past June. It was great. The keepers are so informative. They do describe a little about the backstage areas as you are driving to the safari vehicles, so there is some overlap. Then you get in the safari vehicles and take off on your safari. The trip is really dictated by the animals and where they are in the savannah. It's early in the morning so they are very active. We saw impalas running as a herd, giraffes just about looking in our truck and even heard the lions roar. The guides take their time and really describe the animals behavior and characteristics. They will also answer any questions you have. After the safari there's that great breakfast feast at the Tusker House. The guides attend the breakast too. Our guide sat with us and continued to answer questions.
Hope this helps.