Kalenjin..it depends.. kipsigis n Nandi are 99% similar..other kalenjin also play around 90% percent..if there were major difference you would hear of Nandi fm, Keiyo fm...but nearly all kalenjin listen to same radio station..be it Kass or chamgei or many other stations...because the dialects are very close..the difference really is intonation...more like British and American English.
Of all the nilotics...kalenjin are sort of unique...because the language is only spoken by Kalenjin+Datooga of TZ.
Other nilotics language are related and spoken by many other tribes.
Luo is related to many tribes in Uganda, drc, ethiopia and south sudan - from dinkas, nuer, acholis, many tribes.
Maasai - is close to turkana, iteso, karamojong, many of tribes in sudan and ethiopia.
Kalenjin - ideally should be nilo-cushitic language.
Southern Nilotic languages appear to have been influenced considerably by Cushitic (Afro-Asiatic) languages.[1] The Kalenjin languages are spoken by the Kalenjin people