Summary of Roles

• Administrator – Somebody who has access to all the administration features
• Editor – Somebody who can publish posts, manage posts as well as manage other people’s posts, etc.
• Author – Somebody who can publish and manage their own posts
• Contributor – Somebody who can write and manage their posts but not publish posts
• Subscriber – Somebody who can read comments/comment/receive news letters, etc.

The default role for a new user can be set using the Settings General SubPanel.

See more here:  http://codex.wordpress.org/Roles_and_Capabilities