OG User Roles: Understanding Sitewide Roles vs. Group Roles

The purpose of OGUR is to restrict permissions within a group. In order to do this, you must only use the "Configure member roles" tab to assign roles that you wish restricted within a group; that is, roles whose permissions you want group-limited. See "Configure member roles": http://drupal.org/node/343347.

Any role you assign sitewide (that is, using the core Drupal user edit form) will give a user those permissions sitewide, which also means in *any* group he belongs to.

See this issue: http://drupal.org/node/343096#comment-1141219