It depends. If you ask them for a GPL drop for a particular model, it will be for the same version that was used for that model's released firmware - which is what the GPL licensing requires them to do. The difference in my case is they build the tarballs for all models within a branch but all on the same version, so I don't need to maintain 20 parallel branches to handle 20 devices on 20 different codebase versions. Sometimes, that version will match a released firmware. Sometimes it will be a newer snapshot, depending on the point in time where they prepare those archives. But in terms of content, yes, that is the same code that is available in regular GPL drops. Just it might be from a more recent git point.