XO is named as such due mainly to its bitter flesh and its alcoholic aftertaste. It comparison to the D2, its skin is medium thick while the color of the shell is somewhat brownish green in color. The flesh looks a very pale yellow but is watery and thick. For those of you who likes their durian strong and bitter, then the XO will be a good choice. The shape of the durian tend to be roundish or slightly oval and is usually smaller in size and their thorns point inwards at the base of the fruit.
Souce: The Straits Times