Sub Domain and Directory based?

I believe that’s something you can do with WP Multisite.

I wondered this when reading about converting to networked version. The doc said both are very close but in fact, they seem pretty much the same.

Maybe there needs to be an update in .htaccess in order for both to work?

Now that I’ve spent more time with WPMU, I am starting to better understand it. My question has been partially answered in another thread but not fully.

The answer was ‘why would you want to do that, it would be overly complex’ and at first, I was thinking this is very true.

However. I’m no longer sure this is true. It appears that it would be rather simple for the two to coexist but it is still not clear to me.

I understand that I can install Network plugins and have them network wide or site specific but what is not clear is how these would affect sub-domain users.
Could sub-domains exist connected to the main site while not really requiring to be part of the main site user base? Sub-domain owners would probably not care to be part of any other community and could always create an account on the main site should they want to.

I am trying to reach anyone who might be doing both.