Better known by the names Arabica and Robusta, together they make up almost 100% of the coffee market. Arabica accounts for about 2/3 of the world market and Robusta about 1/3.
Although there are well over 100 different other Coffea species, about 70% of them are threatened with extinction.
Arabica is often called highland coffee because the plant can only grow between 800m and 2200m. This is also why Arabica beans are generally a bit more expensive than Robusta beans.
The bean shape is rather oval and the bean size is generally much larger than Robusta, around 1 cm.
The Robusta beans are smaller and round and measure only about 0.6 cm. Since Robusta beans can be grown up to about 800m, they are often cheaper to grow, but it would not be correct to say in general that Robusta beans are "cheap" and Arabica beans are "high quality". There are both very high quality Robusta beans and inferior Arabica beans.
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