Brown eagles are very difficult. Tawny eagle, steppe eagle, lesser spotted eagle can be very difficult to tell apart. They are all brown, variable (juvenile plumages and colour phases).
The lesser spotted eagle has a relative small bill.
The steppe eagle supposedly a pale throat, while the tawny eagle hasn't. But in light phases of the tawny eagle the throat is light.
Steppe eagle winters in Africa, making it a rare sighting in Africa in during the Eurasian spring, summer and autumn. But I suspect juveniles stick around in Africa year round.
Steppe eagles are larger than tawny eagles, but to estimate size without direct reference in the field is never reliable, both are big raptors!
Tawny eagles often have darker flight feathers and darker tails.
I just went through my pictures and I had 4 labelled as 'lesser spotted eagle' (2 birds). Looking at them again I think 2 of those (same bird) are actually tawny eagle. I have no pictures labelled as steppe eagle, but labelled as tawny eagle might actually steppe eagles.
In theory, in Kenya, greater spotted eagles could also occur, making things even more difficult!