All weapons' descriptions have been rewritten. They now contain several paragraphs: one is a technical paragraph about the weapon, its origin, its charateristics, its use in the real world. Another one is a short background related to its appearance and use into the Zone. Special weapons have further more details about background and technical reference of the upgrade.
Also to mention about weapons in Redux: most of them have became customisable, for instance silencer on the FN2000, or scope and silencer on the Groza. (real weapon names are included)
Most of the changes can be found in the readme here