Arabica and Robusta are two different species of coffee beans that have very different qualities. Arabica tends to be more fragrant and sweeter where as Robusta is sharper and typically more bitter. Most specialty coffees will almost exclusively use Arabica beans for their flavor profiles. Where Robusta coffee shines is in the realm of caffeine. Robusta offers almost twice the amount of caffeine as your average Arabica. It's the coffee bean of choice for many of the best high caffeine coffees. Only around 35% of coffee grown is Robusta where as the remaining 65% is Arabica. One thing to note is that just because a label has the word “Arabica” on it, doesn't guarantee it's good coffee. Arabica, like any commodity, comes in varying degrees of quality. Make sure to do your research about any coffee company you buy from.
– Arabica coffee is more flavorful
Read our full article on comparing Arabica and Robusta coffee.