It is important to make a difference between the Ventus 2 a/b and the c.

Differences Ventus 2a/Ventus 2ax:
-new horizontal stabilizer
-1. gen. maughmer Winglets(2. gen. is already available)

Differences Ventus 2b/Ventus 2bx:
-fuselage of Discus 2b(with 5" wheel)
-new horizontal stabilizer
-1. gen. maughmer Winglets

Differences Ventus 2c/Ventus 2cx:
-new horizontal stabilizer(iam not sure)
-1. gen. maughmer Winglets(2. gen. is already available)
-higher mtow of 600kg instead of 525kg)

Differences between DuoDiscus/DuoDiscus X:
-additional flapps in the inner side of wings which are combined with the brake flapps and which decrease speed.
-750kg mtow instead of 700kg