Arabica coffee flavor can be described as fragrant, sweet, round, slightly acidic and often chocolaty, with a light hazel to reddish crema and a pleasant bitter note. Robusta coffees by contrast are sharp and astringent, with little fragrance and greater bitterness. The crema tends to have a brown-grey color.
The Arabica bean is elongated, with a sinuous groove. The Robusta bean is rounder, with a straight groove. While Arabica and Robusta differ only slightly in appearance, they are genetically quite distinct: the first has 44 chromosomes, the second only 22. The caffeine content of Arabica ranges from 0.9 to 1.7% while the Robusta species is much higher at 1.6 to 2.8%.