Performance
As far as horsepower, the FX50 packs quite a wallop and will knock the Lincoln Navigator L down a few rungs. On the other hand, bear in mind that high horsepower engines often command higher insurance premiums.
Handling
With its tighter turning circle, the Infiniti is most certainly more maneuverable than the Lincoln Navigator L, something to consider if you do a lot of city driving; on the flip side, note that a vehicle with a tight turning circle may feel a bit twitchy on the highway.
Drivetrain
The Infiniti FX50 and the Navigator L have similar-sized engines, with a slight advantage to the Navigator L.
Utility
Drivers with frequent kid-duty might favor the Navigator L over the Infiniti.
The Lincoln Navigator L is a better choice than the Infiniti FX50 with respect to transporting cargo, especially if you often need to carry a lot of loot or massive pets.
Towing is considerably more the Lincoln Navigator L's forte than it is the Infiniti FX50's.
Comfort
While the front cabin in the Lincoln Navigator L offers a bit more head room than the FX50, there frankly isn't much of a difference.
The ampler interior dimensions of the Lincoln Navigator L make it considerably more spacious for your passengers than the Infiniti FX50.
Dimensions
The Lincoln Navigator L is tremendously more bulky than the Infiniti FX50.
Your wallet will hurt more every time you fill up the Navigator L than the Infiniti FX50 because of its bigger tank.
The Infiniti FX50 fits in smaller parking spaces than the Lincoln Navigator L.
The Lincoln Navigator L's longer wheelbase will likely result in a smoother, more stable ride; however, the Infiniti FX50 may give a nimbler feel in daily traffic.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs approximately the same to get the Infiniti FX50 to the dealership as the Lincoln.
As far as MSRP, the Lincoln Navigator L costs almost as much as the Infiniti FX50 (though the Infiniti FX50 is slightly cheaper).
Warranty
The basic warranty that comes with the Lincoln isn't quite as generous as the Infiniti's.