Solid frame, fixed roll cage in roughly the same location as current sport bar
Fully removable roof
Fully removable doors
Overall vehicle and windows/windshield appear taller above the belt line (more headroom and better visibility?)
Turns signal on side mirrors which are attached higher on the doors (within new window moldings) than current JKU.
the rest of the list of changes are at http://www.jlwranglerforums.com/here-is-the-real-2018-jeep-wrangler-unlimited-rubicon/
But... lemme tell you something as a guy that photographs Wranglers for a living... yup, I work at a Dodge Jeep dealership, and I'm in the new stuff every mon-friday... this really isn't very different than the 2017 stuff we have right now.
But no one takes the doors and tops off of them in town, so... heck, I've never seen one with all the panels removed...