There are six species of Baboon: 
1. the Olive Baboon (Equatorial Africa), 
2. the Yellow Baboon (Eastern Africa),  
3. the Chacma Baboon (Southern Africa),
4. the Kinda Baboon (Angola, Congo, Zambia),
5. the Guinea Baboon (Western Africa), and 
6. the Hamadryas Baboon (Ethiopia, Somalia and Yemen). 

The largest is the Chacma Baboon (up to 1.2m) and the smallest is the Kinda Baboon (up to 50cm).
Tanzania has the Olive Baboon (North) and the Yellow Baboon (Central, South and coastal Tanzania).
The Yellow Baboon is a lighter built, leggier animal than the Olive Baboon and is not as dark in colour, being a light olive brown as opposed to dark olive grey.

Lake Manyara National Park, Tanzania, 10 & 11 January 2008