Taste
Arabica beans have a milder, more aromatic taste while Robusta beans hold a stronger, more acquired flavour, with a grain-like overtone and peanutty aftertaste.
Arabica beans tend to have a sweeter, softer taste, with tones of sugar, fruit, and berries. Their acidity is higher, with that winey taste that characterizes coffee with excellent acidity.
Robusta beans contain twice as much caffeine as Arabica beans.
Shape
Arabica beans are flat and elongated while Robusta beans have a more obvious rounded shape.
Price
Due to the fact that Arabica is the more flavoursome of the two types of bean it also fetches a higher price. Higher quality coffee blends consists of 100% Arabica coffee beans while cheaper blends are usually made up of a mix between the two beans. These are often considered to be of a lower quality.
Quality
Robusta beans contain a higher level of caffeine than Arabica beans. This factor may be a decision maker for some people when choosing their coffee as Robusta beans contain almost double the amount of caffeine and they are generally considered to be of inferior quality compared to Arabica. Some robustas, however, are of high quality and valued especially in espressos for their deep flavor and good crema. Robustas, however, are easier to grow. They can grow at lower altitutes than Arabicas, and they are less vulnerable to pests and weather conditions. They produce fruit much more quickly than the Arabicas, which need several years to come to maturity, and they yield more crop per tree.
“Robusta is not lower quality. It’s just that globally, people have learned to drink Arabica coffee,” Vu told AFP in an interview at the Trung Nguyen Village in Buon Ma Thuot. Source from http://www.japantimes.co.jp/news/2013/04/21/asia-pacific/vietnam-brews-global-coffee-takeover/#.UXL07b-BBic
Facts
Brazil is the world largest coffee producer and major exporter of Arabica beans
Vietnam is the world