1st , let's exclude the issue of dirt/water/sediments/bacteria! in the fuel (which can be avoided simply by using a filter )
Well , one of the ways to measure the quality of diesel fuel , is in the easyness of igniting (flash-point) under a certain temperature.
Easier-(lower temperature required) means much more complete combustion (diesels polute air mainly by not-fully burning all the fuel inyected 'cos either low-combustion chamber temperature , either low compresion , or low-quality fuel.
In this way , African fuel will for sure burn poorer (hence white-diesel smoke ).Its just a heavier fraction , with higher ignition point , and definitely burn poorer at a given conditions .
Also , there's the issue of Sulfur content , with the new "eco-diesel" , European diesels have cut the sulphur content in diesel almost to zero , while in Africa , diesel has all its sulfur content , which makes kinda lubricant for the fuel (inyection) pump . In this way , older diesels (Land rovers Series , etc..etc. ) will certainly suffer more wear with European fuels than with African ones.
Say that African diesel is much more "heavy" ,and "lubricant" than the new eco-diesel stuff.
There's also the issue of Nitrile ,Neoprene and Viton gaskets in the inside off the fuel pump . In order to cope with the new (European ) more volatile -smaller fractionated- and actually thinner diesel fuels , new rubber matterials are used in the o-rings ,seals ,etc.. of the inyection pumps. These new seals will grow/inflate/soak under old-style african diesels.
If unsure , a good (and illegal) way to test-run the suitability of a given engine to run on 3rd-world diesel is to run it on heating diesel. Heating diesel -blue or red- (Gasoil) is practially the same as what is sold as diesel-fuel in Africa.
Having said that , most old-style diesel vehicles (mechhanical fuel inyectors ,CAV /Bosch style rotodiesels) will run actually better with African fuels than with eco-diesel.
Hava nice day.