WordPress Expert

Supports one blog with multiple bloggers.

Supports multiple blogs and multiple bloggers. Bloggers can write for multiple blogs.

Famous for its “5 minute install.”

Setup is more involved.

No advanced hosting requirements.

Your host needs to support wildcard DNS to use the subdomains feature.

Instant installation (through Fantastico, etc.) supported by many webhosts.

FTP time!

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.

WordPress lets you specify whether or not gzip compression of articles is available.

WordPress MU lacks this option.