these two replies are helpful:
Sport - Bottom model ...
Sahara - more plush sport ...
Rubicon - more off-road suspension ...
Willys packages have features of Rubicon without being a Rubicon...
IMHO that should read
"Rubicon - more rock-crawling specific options ..."
Some of the Sahara's, particularly the ones with the "Max Tow" option will have exactly the same suspension as a Rubicon except for the Axles.
I prefer TruTrac LSD's and Manual Transmissions, as the Rubicon lockers are proprietary it is not an option to swap them out, so I just looked for a Sahara with 17" Rubicon wheels and red shocks.
As this is an expedition directed site it is important to note that the "upgrades" on the Rubicon line are tailored to a use case that mirrors the trail it was named for. This means that the features are optimized for rock crawling, and will only operate at lower speeds or other limitations.
Some options to consider is that not available on the Sahara from the factory are:
Rock Rails
Electronic Front Sway Bar Disconnect (restricts your speed electronically, almost all my friends have installed manual disconnects on there Rubicons)
Front electronic locking diff (rear is optional on the Sahara)
Dana44 front axel
The Rubicon has Dana 44 front axel, while the Sahara uses the Dana 30, if you are going bigger than ~35" tires and want lockers this may be an issue that will result in higher costs. I have gone everywhere from the Arctic Circle in December via the Dempster to multiple trips on the Mojave road. With TrueTrac LSDs front and back I personally haven't had an issue with the Dana30, but I have worn out lots of tie rod ends, shocks etc.
One other consideration is that the Rubicon has a 4:1 transfer case ratio when all other models are 2.72, I haven't found this to be a problem on the 6-speed but have never driven an auto off road. As my JK has a manual I am planing swapping in a 4 speed atlas because turning around in 2wd in tight spaces has nearly caused me issues before so this wasn't a consideration for me. The 4 speed atlas is not an option on the auto transmission JKs, but the 2 speed is.
But in general, outside of the trim level aesthetics, the lower ratio transfer case and the lockers are the main differences to consider. If you like lockers the Rubicon can cost less, especially if you don't do your own work. I should point out that they cannot be engaged above 10 mph and at 45 mph they disengage, so many people bypass the stock system.
That said the "BLD" system works on all models, or better than I expected so the Rubicon lacking LSD, or the lower models lacking lockers will not dramatically reduce your ability to go off road. I was a bit concerned in some fast runs in sandy washes by the power cut so I did end up installing the TrueTracs front and rear as planned, but to be honest it was not as dramatic of an upgrade as I expected due to my experience with older vehicles that lacked modern traction control/bld.
It is frustrating that functional components are tied to trim levels, so hopefully this additional information helps others out.