Difference? Aquia CST414M and CST416M

What's the difference between Aquia CST414M and CST416M?
Does one have CEFIONTECT, and the other not? Something else?
Thx!

The one uses the U shaped adapter and the bowl slides toward the back wall.

The two and the three will use the flange adapter, and the bowl drops straight down on it.

The One has an open back, the Two has a closed back bowl.
In the Seattle area, we are stocking the II and the III, the I is a factory order for us.