The difference is that if a file isn't sorted in a file system, it just sits on your Desktop or Download folder and is still easily visible. If you use tags and your file doesn't get tagged properly it just is lost in the pile and impossible to retrieve.
I find tags work very well for discovering other peoples content on the web, but really don't help much with organizing your own data.
One operation that seems especially problematic with tags is copying. If I want to modify something on a file system and keep a backup, I just copy the directory tree before I do my modifications. If I copy something with tags, I end up with two things with the same tags, which is not very useful for keeping them separate.
Also how do you deal with removable media (USB, DVD) in a purely tagged system? What if the tags on the media conflict with your own tags? Once you allow filtering by device, you are just reinventing the file system again.
I find tags work very well for discovering other peoples content on the web, but really don't help much with organizing your own data.
One operation that seems especially problematic with tags is copying. If I want to modify something on a file system and keep a backup, I just copy the directory tree before I do my modifications. If I copy something with tags, I end up with two things with the same tags, which is not very useful for keeping them separate.
Also how do you deal with removable media (USB, DVD) in a purely tagged system? What if the tags on the media conflict with your own tags? Once you allow filtering by device, you are just reinventing the file system again.