I feel that the Tag is the most simple kind of taxonomy, I mean there is absolutely no business ideas in them, they are just there so you can tag multiple thing

I feel that the Tag is the most simple kind of taxonomy, I mean there is absolutely no business ideas in them, they are just there so you can tag multiple things with different keywords. The playlist on the other hand since it inherits from tag I could potentially add some features to it, like only a certain group of user can access certain playlists. In terms of the significance to end user, being able to put different types of taxonomy into different "named" groups help people visualize them differently, I feel. People think of tags differently from playlists. Hence if you try out the filters on the posts page of our site, you can only view one playlist at a time, but you can activate multiple tags at once. I hope that helps.