Scoped searches are pre-filtered searches (similar to Kagi lenses, but with more customization options); tags are similar to bangs but filter/restrict to a domain instead of redirecting to it (similar to Kagi snaps).
You can also now customize the prefix character for bangs and tags (and scopes can have a tag set as well, so you can do "@s barcelona" for a "barcelona" search with a "Sports" scope, for example).