Performance wise they are pretty close.
In one recent test that others have done,
The Drake moves 900 grams of waste and the
Ultramax moves 700 grams.
To put this in perspective, many toilets on the market will move less than 200 grams
and some have a hard time moving 100 grams.

The Ultramax does come with the softclose seat, has the one-piece design, and is a little quieter than the Drake.