AppArmor 2.6 is incremental improvement over AppArmor 2.5, that has focused on bug fixing and internal cleanups of the userspace code over new features. AppArmor 2.6 is purely a userspace release, it leverages the same kernel code as AppArmor 2.5.
http://wiki.apparmor.net/index.php/ReleaseNotes_2_6_0