I was going through the migration from bs3 to bs4 and found that the migration guide says:

Renamed .label to .tag to disambiguate from the element.
Dropped the .badge component as it was nearly identical to labels/tags. Use the .tag-pill modifier together with the label component instead for that rounded look.

But according to the documentation Badges still exists and tags do not

https://v4-alpha.getbootstrap.com/migration/#labels-badges-and-tags