First of all, all Twist types are universal adapters. Every one of them will work on any power outlet in the world.
However, only TWIST Plus Wolrd Adapter has the Universal Outlet feature. What the feature means is a power plug of any type can also plug into the TWIST Plus World Adapter and piggback of it. This means you don't have to lose a socket if you have to charge your MacBook.
Becuase this feature takes away some internal space, Twist Plus World Adapter has ONE USB port instead of 4 USB ports, making it a well balanced world travel adapter.