The Fluid uses the Fluid flex rail system for binding interface, while the regular version is a flat ski. While free flex plates/rails etc are not new news, they can do some things and in this case, it may be a pretty good thing. The Fuid rail has a flatter stance than the more traditional Look bindings have had. This removes one of the few niggles that some folks have expressed over the Pivot and the PX ie: some think it has a bit too much ramp. This is not a huge nor dramatic difference, but for some it will be an improvement. The shape of the ski is changed somewhat as well with a new more contemporary sidecut. Again, no big deal just an incremental improvement to a ski that many think is already about as good as the genre gets.
Naturally, if one were allergic to binding rails, the flatter stance could be emulated with any number of bindings and some judicious perusal of spacer/lifter heights.