Um, was the modification that they had to change “AT&T” to read “Verizon” in the name?
Seriously, I’ve tested dozens of apps on both phones now. Including several location-based apps that use GPS. Both versions of the phone run each app the exact same, unmodified.
Further, talking to Apple about this, they’ve made it very clear that all apps will run the same unmodified except for the ones that AT&T and/or Verizon themselves may release.