The number of different panels mean little when the changes are so subtle. In my opinion, the Cobra has a conservative appearance, even more than the GT or V6.That is completely wrong. The Cobra has more model specific panels than a Mach 1. They have Cobra specific hood, front and rear bumper, mirrors and spoiler. It looks nothing like a GT. The panels make it appear lower and wider.
The cobra doesn't so much look like a GT, but rather is looks less than a GT. It doesn't stand out and look different, instead its visual difference is in what it does not have.
Again, I don't mean that in panels, but rather from the spectators point of view.
The Mach has always been styled agressively, from its original debut in 1969 onward. It was the first true muscle mustang, and Ford's response to the muscle car wars.
The Mach's usually stand out with contrasting colors and bold black accents that give a very agressive, race-like presence. The black deck spoiler,black chin spoiler, black stripes, and shaker are throwbacks to the original Machs.
Additionally the flared out rockers match well with the conveniently scoop styled bumper also accented by the chin spoiler give the Mach a flared and broad appearance.
The C-panels are different too, they are scoop like and not sloped like the GT/Terminator.