As far as naming - here is a quick summary;
We are talking "Wrangler" in this discussion, which is the model of the Jeep.
There are 3 basic trims
SPORT
SAHARA
RUBICON
All models of the wrangler are trail rated, and feature 4-LO.
All can be upgraded to be EXTREMLY OFF ROAD capable, including Rock Crawling.
Most people start with Sport, and then add what they want. Same thing can be said of Sahara - add more offroad ability once you determine what you want.
There are models in between, but they are just packages with mopar parts preselected, and generally stuff that makes the jeep look different. Do not get side tracked by things like "Willys" "Altitudte" "Moab" "Recon" etc...those are just special edition packages.
The Sport is the basic trim. You cannot add some items to the sport.
The Sahara is the "Mall Crawler" edition - full luxury, perfect options for everything, and very suitable for those whose idea of offroading is staying on a trail that might be bumpy. It can do 90% of what a stock Rubicon can, just not as comfortably in it's stock form. Specifically, the gear ratio is a 3.21 vs 4.10. This limits the overall height of tire you can do prior to needing to upgrade.
The front axle on the sahara is a DANA 30 --- good solid axle, but not suitable for rock crawling.
Sahara comes with stock 18" wheels -- they look very nice. I actually put these on my daughters JLUS (Sport)
The Sahara is also the only one with the ability to have selectTrack AWD transmission - again, very nice for those that live in snow country and use as a daily driver.
The Rubicon has 2 main options that make it a more trail capable and comfortable
* Electronic Front Sway bar disconnect
* Front + Rear Lockers
The sway bar disconnect can be done on ANY jeep, but requires getting out, and removing a bolt or a pin if you install a quick disconnect. On the Rubicon, you press a button. This makes rough road driving VERY comfortable, and with an easy mod, you can do this up to any speed in 2WD. You would not want this disconnected for smooth roads or highway use, but for trails, it is a very nice feature.
Front + rear lockers are huge. This feature alone is why I chose Rubicon. Getting out of a situation where a single wheel slips is imperative. Only possible with a locker. Adding lockers after the fact is a huge undertaking and expense. MUCH cheaper to start out right.
If for no other reason, choose Rubicon for the lockers.
You can easily add *every* option of the Sahara except 18" wheels and SelctTrac transmission.