| Each user is assigned a role level (subscriber, contributor, author, editor, administrator). | In addition to the standard WordPress roles, you can also specify “site admins” who can add/edit/delete all blogs and users. |
| WordPress receives updates first. | MU users must wait for WordPress updates to be applied to WordPress MU. |
| Administrators can edit themes, plugins, and code files from within WordPress. | The Theme Editor, Plugin Editor, and Manage Files sections are all disabled for security reasons. |
| Plugins can be enabled/disabled by the blog administrator. | The site admin can opt to have plugins disabled altogether (the default setting), or allow blog administrators to enable/disable plugins that have been uploaded.Plugins can also be uploaded to a special “mu-plugins” folder, where they will be executed automatically on all blogs. (Some plugins won’t function property when run this way, however.) |
| If you have multiple blogs running standard WordPress, you’d need to upload plugin updates to each one. | Plugins for all WordPress MU blogs are stored in one place. Update once, and it takes effect on all the site’s blogs. |
| If you have multiple blogs running standard WordPress, you’d need to login to each one separately to access the administration. | You can switch between blog admins using a simple drop-down menu. |
| Allows you to use most HTML in your posts, but strips out PHP. | In addition to removing PHP, WordPress MU is more strict in regards to what post HTML it accepts. For example, it will strip out class/ID attributes, inline styles, <span> tags, etc. |
| WordPress allows posting via email. | WordPress MU lacks this feature. |
| WordPress lets you customize its list of update services. | WordPress MU doesn’t let you specify update services. |