Arabica coffees are mostly grown at higher altitudes: Temperatures on the mountains are lower than in valley locations, slowing the ripening process of the coffee cherry and thus the development of the sugars, resulting in a richer flavor profile and higher acidity.
At lower elevations, the cherries ripen much faster, so the coffees become less complex as the cherry reaches full maturity more quickly.
Arabica coffees achieve more complex flavor profiles due to lower temperatures.