You live in a place where the speed limit is 60,
and with luck you can find a time & place where you can get away with going 100.
Your choice is a car that can do 140 (Simple) or a more expensive car that can do 180 (Simple Ultra).
Both offer performance far beyond what you can typically use, but its really fun to drive a high-performance car,
even if you can't use it to the max.
If you're looking for the ultimate special occasion diaper, maybe the Ultra is the way to go.
If your looking for a 24/7 (or frequent use) diaper, the basic Simple is significantly cheaper, and will never let you down.
Either one is a great value.
One key difference is bulk & thickness. The basic Simple is wider & thicker, and definitely more noticeable.
The Ultra is newer technology with even more SAP, so it manages to be less obvious, even though it can absorb more liquid.
(Of course, either diaper fully-soaked is going to be pretty noticeable