Sharepoint: site collection administrators vs. site owners

Site collection administrators

These administrators have the Full Control permission level on all Web sites in a site collection. They have Full Control access to all site content in that site collection, even if they do not have explicit permissions on that site. They can audit all site content and receive any administrative message. A primary and a secondary site collection administrator can be specified during the creation of a site collection.

Site owners

By default, members of the Owners group for a site have the Full Control permission level on that site. They can perform administrative tasks on the site, and on any list or library within that site. They receive e-mail notifications for events, such as the pending automatic deletion of inactive sites and requests for site access.