It's certainly a major departure from the little boxy Grumman. Most noticeable is the considerable increase in height. It's tall enough that it actually has clearance lights on the top. Besides that, you can see how much space there is between the top of the driver's head and the top of the windshield. It looks like the cabin continues up into the roof space above the windshield, too. One big upside to this design is that the driver should be able to stand up comfortably in the front of the truck if needed. that added height continues into the cargo area, so this probably has greater capacity than the old Grumman.
Besides the size, this Karsan has a much more detailed exterior than the slab-sided mail trucks of today. It has rugged, bolt-on plastic fender flares, bumpers with ribs and a tough, angular grille and headlight pods. The lower section that houses the engine is longer and more horizontal than the Grumman's, and the windshield is bolt upright. There are more plastic components wrapping around the cargo box, too.
This may not be the only mail truck, though. The U.S. Postal Service said that it's considering operating a variety of trucks for different purposes, as opposed to a one-size-fits-all approach. This could mean other Karsans in addition to this one, or perhaps different vans from different makers. This and other mail trucks may be hybrids or some other alternative fuel vehicle, since reducing emissions is one of the U.S. Postal Service's goals, and it previously said that half of the test vehicles use hybrid or alternative fuel tech. Based on the organization's timeline, it should be ready to award final contracts toward the end of 2018, with the production roll-out beginning in 2019.