Jambo has three restaurants: Mara a counter service with lots of seating, Boma one of the best buffets on site, and Jiko a very good but pricey table service. Kidani has only a table service restaurant, Sanaa, which is not open for breakfast, but it is in my view is one the best on site, although also on the high side (for me anyway) but cheaper than Jiko. Yes, you can walk, take bus, or take shuttle between resorts but distance from door to door is about 1/2 mile.
Jambo's lobby and store are much larger than Kidani's and the Jambo store is the better place to shop.
Jambo has the siginficantly larger pool and has many places to find shade as trees and bushes are all fully grown, while Kidani is essentially shadeless anywhere near the pool. Though the Kidani pool is smaller, it has the much longer slide and the best kid's water play area of any of the resorts.
All Jambo rooms are on fifth and sixth floor (sixth floor has only the club level rooms and exists only directly above the lobby). At Kidani, they are all
DVC rooms on all four floors (2-5). Lower floor allows more direct line of sight to the animals, but there is nothing wrong with higher floors.
If you have a rental car, the Jambo lot is across the street from the front of the resort and parking can be anywhere from fairly near the front entrance to a long way off. The Kidani lot is ideal in that it runs under the Kidani building, and at spots just outside the building but part of the same lot, and with three elevators along each of its wings, you can always find a space that is fairly close to your room no matter where your room is.
Kidani has a very good Community Hall, Janbo does not have one.
For either building you can have a long walk from room to lobby but for Kidani that walk can be record-setting in distance (up to about 1/3 mile down a hallway).
Jambo has three savannas. Arusha in the middle of the building is the best one there. It shares Sunset, the largest and also very good savanna with Kidani. It also has Uzima which is good. Sunset Savanna at Kidani has giraffes, Pembe does not and personal view is that Pembe looks too much like an afterthought designed to fill a fairly small space; it is OK but the worst of all the AKL savannas.
Studios are about the same size in both buildings (contrary to what is mentioned above). Jambo houses the toilet and tub/shower together in a separate room. Kidani has the tub and shower in the open area where the sink is, thus creating a privacy issue for use of sink and tub by two different persons. Kidney has better closet space.
The Jambo Grand Villas are single story with a room having a pool table, a master bath with a large TV viewable from the tub, and the largest porches available of any GV's on site. Kidani's two-story GV's have an extra pull-out couch at the alcove at the top of the stairs.
The Kidani 1BRs and 2BRs are about 100 sq ft larger than the Jambo rooms (the difference is very noticeable), have more closet space, the much better master bath where the tub and shower are separate (Jambo has a combined tub and shower and the tub takes a high step over to get into). The master bath at Jambo is separated by a hallway from the master bedroom, which hallway can be seen from the living room. Kidani has an extra bathroom and master bath requires entry from the master bedroom.
Loved relaxing after getting my morning coffee admiring the gorgeous lobby and Christmas tree! 
Can't go wrong at either...ENJOY!
