NOTE: Dieseldorff exclusively uses Arabica coffee in all it's blends.
Arabica coffee is coffee made from the fruit (commonly known as the "cherries" or "beans") of the Coffea arabica varietal of coffee plant. Arabica coffee is most widely produced type of coffee in the world, comprising about 70 percent of the world's coffee production, despite the fact that the second-most popular varietal (Robusta coffee from the heartier Coffea canephora plant) is much easier to grow and produces much higher yields.
Arabica coffee is considered superior to Robusta coffee for several reasons. It has a much more delicate, rounded flavor than Robusta and many other varieties of coffee. Although there are many types of Arabica coffee available from many different parts of the world, Arabica coffee beans can generally be described as sweet and soft, with notes of berries, other fruits and sugar. Many have a "winey" note (akin to a bold red wine, with plenty of acid and tannins). Some are sharp and tangy, while some have a distinctive blueberry note after roasting, and some are floral, light and highly fragrant.
Arabica coffee is generally much more expensive than Robusta coffee because it is harder and costlier to grow, it produces a lower yield and it is in higher demand. Many of the world's more expensive coffee blends are produced with only Arabica blends, while cheaper coffee blends tend to contain more Robusta.
The Coffea arabica plant is a delicate tree. (Compare to the hearty C. robusta shrub.) It requires plenty of care, a cool, tropical climate, and moist, rich soil to thrive. The tree usually prefers an altitude of 600 to 2000 meters. It is vulnerable to cold weather and to many pests.
Arabica coffee is much lower in caffeine than Robusta coffee. Estimates range from half as much caffeine to 2/3 as much caffeine.
(From www.coffeetea.about.com)