Question: What's the difference between Robusta and Arabica?
Answer: You hear about Arabica beans mostly, and that's because they make better quality coffee than Robusta. Arabica beans have much more flavour to them, and are the typical bean in all but the cheapest coffee. Inexpensive coffee may have Robusta beans blended in, but will almost always have some Arabica.
As a twist, Robusta beans have nearly twice as much caffeine as their better-tasting cousins.
The two are actually different species of the coffee plant, rather than just varieties of the same plant. Arabica beans come from the <i>Coffea arabica</i> plant, and Robusta from the <i>Coffea canephora</i>.