Administrators have full power over the site and can do practically everything. They have complete control over posts, pages, uploaded files, comments, settings, themes, imports, users – the whole shebang – including activating already installed plugins. (Site Administrators cannot install new plugins, though.) Administrators can even delete the entire site, which is why we recommend having only one administrator per site.
Editors can create, edit, publish, and delete any post or page (not just their own), as well as moderate comments and manage categories, tags and links.
Authors can create, edit, publish and delete only their own posts. Authors do not have access to create, modify or delete pages, nor can they modify posts by others.
Contributors can create, edit and delete their own posts, but cannot publish them. (A site Administrator must approve a Contributor’s post before it is published.)
A Subscriber can read posts, even on a site that might otherwise not be open to the public.