Board Thread:Boruto Discussions/@comment-32196880-20170910080526/@comment-6769189-20171014050509

Clans are more of a family structure. It is a binch of inter-related families that have formed a community. Since the Uzumaki clan structure is gone, and has left only a few members of the Uzumaki bloodline alive.

Not every family belongs to a clan. Since the Namikaze have not been mentioned to be a clan, then we assume that is a bloodline that follows a narrow familial structure (parents to children, maybe with siblings and a few cousins) rather than a a large group of families who share ancestry and are only distantly related to other families.