The distance from front door of Kidani to front door of Jambo is about 1/2 mile. There is a shuttle bus that runs between the two during the day and evening.
The hotel rooms and studios at Jambo are comparable in size to the studios at Kidani, but allow only four plus a child under 3. The Jambo DVC rooms are on the fifth floor (and sixth for club-level) and floors below that are hotel rooms. All rooms at Kidani are DVC. If you will be getting a 1BR or 2BR, the 1BRs/2BRs at Kidani are better. They are about 100 sq ft larger than the ones at Jambo, and have an extra bathroom (near the front door). Only Kidani has dedicated 2BRs, which have two queens in the second bedroom instead of a queen and pull-out couch; all Jambo 2BRs are lockoffs with a queen and pull-out couch in the studio. Kidani has more closet space than Jambo. And the master bath in the 1BRs and 2BRs at Kidani have a tub and separate shower, while Jambo has a combined tub/shower, and has a high stepover to get into the tub.
Both resorts have comparable and very good kids activities during the day. The pool at Jambo is larger than Kidani and has more shaded areas, but Kidani has the better and longer slide into the pool and has a nice large kids water play area. Jambo has three restaurants, Jiko, an expensive but good table service restaurant, Boma, one of the better buffet restaurants at WDW, and Mara, a counter service restaurant that has lots of seating, including outside towards the pool. Kidani has only a table service restaurant, Sanaa, which is very good and less expensive than Jiko. The lobby at Jambo is larger than Kidani's and its store is much larger than Kidani's.
Buses to and from parks run Kidani to Jambo, except that during early morning rush each usually has its own bus to MK. Bus to and from Disney Springs runs Jambo to Kidani.
The Jambo u-shaped building is large and walks from end rooms to lobby are long. However, nothing compares to Kidani, which, at close to 2/3 mile long, is one the longest hotel-like buildings in the world (and by world, I mean on earth, not just Disney World). If you have a car, Jambo has a large lot across the street from the front entrance, and walk can be fairly short to long depending on where you can find an open space. Kidani's has an under-building parking lot, which is the first floor, that runs nearly from one end of the building to the other, and with three elevator locations along each of the two wings, you can usually park fairly close to your room regardless of where the room is located.
If reserving through DVC or a DVC renter, one can make room location requests through Member Services. There is also a room location request page provided during online check-in but requests one can make are limited and some are pointless, e.g., you can request near an elevator at Kidani, but, since you cannot name the particular elevator on that online check-in page, such a request could result in your being placed in any room in the building.
If you have Savanna view at Kidani, and have a service (such as DVC MS) through which you can make specific requests,I recommend requesting a Sunset savanna view (which has giraffes and zebras; the smaller Pembe savanna does not) and a room near the Rafiki elevator (on the north wing not very far from the lobby and it provides the shortest walk from the building to the pool), or near the Timon elevator (on the south wing, not very far from the lobby, and down that elevator to second floor leads to a door that exits directly to where the bus station begins). If savanna view at Jambo, I would recommend requesting a room on Zebra trail with Arusha savanna view (one in the middle of the u-shaped building), and away from the lobby -- rooms away from the lobby provide better views and an Arusha savanna view from a room along Zebra Trail means the room will face west and thus avoid sun coming into the room in the morning. have a shaded balcony until afternoon, and provide pleasant sunset views.