Dripped Content Site

I've not noticed these options before, but what does "Dripped Content Site" and "Advanced" mean?

What additional options are these for? I tried searching but the search feature doesn't bring up anything related to this.

Here is the message:

Welcome to Membership
If you need help getting started, check out our documentation over on WPMUDEV. You can use the Help tabs in the upper right corner to get information on how to use your current screen. If you would like us to set up some basic things for you then choose an option below.
Standard membership site.
Dripped content site.
Advanced.

Thanks,
Kim