The majority of Vietnamese coffee is made from Robusta beans. Vietnam is the biggest producer of this coffee variety in the world. More than 90% of coffee produced in the country is made up of Robusta beans. It has strong, harsh and bitter taste and grows in the southern Central Highlands region. Generally, growing Robusta is quite easy: it grows at flat areas and adapts to the most of Vietnam's natural conditions. It also has roundish shape that distinguishes it from another type of coffee – Arabica.
Arabica in comparison with Robusta is a more whimsical plant. It requires stably warm temperature, which doesn't fall below +15 °C, and regular sunlight. Arabica can’t grow at flat terrains and grows as high as possible above sea level (starting from 1500 meters). There are some requirements to the soil condition as well. It must be fertile and abundant, and the plant itself must be regularly protected from the insects.
The conditions of growing Arabica and Robusta undoubtedly affect their taste. Arabica has a delicate and pleasant taste, while Robusta is bitter and rich.
You can learn more about differences between Arabica and Robusta here