Their main differences are to be found in taste and where they are grown, and the first major difference is genetic: Arabica has 44 chromosomes and robust 22, robust also contains a higher level of caffeine than Arabica, even twice as much. This factor is important to consider for those who have difficulty getting sleep after drinking an extra coffee. Arabica (which by the way is 70% of the world's coffee) is most cultivated in South America, Central America and Africa of the "reefs", Kenya, Ethiopia and East Africa in general. The robust, on the other hand, is produced on average by West Africa (Cameroon, Ivory Coast etc.) and in the Far East (Vietnam and Indonesia first). In addition to this the Arabic grows at best at high altitudes, above a thousand meters and needs a lot of rain, while the robust also grows at lower altitudes and in conditions, say, less ideal in terms of humidity and soil type; it also has fewer problems with diseases.