SP2010 to 2013 migration, on-site, not online.
Migrated users see a large list of apps on both the parent site and its subsites.
New (since the migration) users see only five apps on the parent site. Four of these five are available to the migrated users, but one (Access App) appears only for new users.
On subsites, new users see the same list of apps that migrated users see. They also have the one app that the new users do not.