"I consider any emblem or label a prejudice." -Anton Chekhov (1860-1904)
Labels identify something or someone. They may designate origin, use or destination. They adhere; they are difficult to remove.
Tags, in information technology, are keywords or terms assigned to a piece of information. They are usually chosen informally and personally by the creator or user. They are flexible; a single item may have more than one tag.
Labels are limiting; tags permit infinite variation.
"The only sin is limitation. As soon as you once come up with a man’s limitations, it is all over with him." -Ralph Waldo Emerson (1803-1882)