Arabica beans contain much less caffeine and fewer chlorogenic acids than Robusta beans. Instead they contain more oils, which gives them a more intense yet much milder flavour. Most premium coffees are made from Arabica beans, but not every Arabica coffee is a premium coffee.
After the beans are hulled, they go through a final classification process. Once any remaining residue has been removed, the beans are sorted according to size, density and colour. This process results in a range of different qualities on the market. Both Arabica and Robusta varieties may be available in different qualities.
To add to the confusion, the names used for different quality grades vary from country to country.