There are two main varieties of coffee beans: Arabica and Robusta. Arabica beans are considered to be of higher quality and are grown at higher altitudes, while Robusta beans are hardier and easier to grow, but are generally considered to be of lower quality. Arabica beans are also sweeter, milder, and have a more complex flavor than Robusta beans, which are bolder, nuttier, and have a more bitter taste.
Within these main varieties, there are also many different subtypes or cultivars of coffee beans, each with its own unique characteristics. For example, some popular Arabica cultivars include Bourbon, Typica, and Caturra, while some popular Robusta cultivars include Catimor and Congensis. The specific variety of coffee bean used can have a significant impact on the flavor and quality of the resulting coffee.