WPMU vs WordPress MultiSite is there a difference anymore?

I realize that WPMU used to be a separate product from WordPress and now is bundled with WordPress as a deliverable. What I’m looking to find out here is the difference between WPMU and MultiSite? Is there a difference? Have they merged?

I’m having a hard time finding this seemingly simple answer even on WordPress Codex.

Being that this has become a subject of debate amongst myself and some of my colleagues, an answer to this question would be very helpful, but I will need to see proof in answers! (links to references)

All the research I perform points to Multisite when I search WPMU or Multi Network. I can not find an end date (EOL) for WPMU or a date when WPMU and MultiSite were merged, or if they even were.

If anyone could shed some light on this matter it would be very helpful and also a determining factor in how we will use WordPress going forward.

Thanks in advance, what I thought would be a simple answer is turning out to be quite difficult to find.

Since version 3.0 there is no such product as “multisite” neither by name nor by code (mostly anyway), it is just another configuration option of wordpress, one that requires some extra admin work to activate, but essentially it is not some separate code base.

When there is a reference to “multisite” today, it is a reference to the configuration, not a product. WPMU itself is a term I haven’t seen being used for years.

The merge ticket is #11644 and it was fixed/closed in the year 2010.