Thank you for that link Fluffy.
Now that I know of the technical terminology where:
The Wireless ISP (WISP) mode is a combination of the Bridge and Gateway modes, in which the router still relies on the main gateway to provide access to the internet, but it retains use of the built-in firewall and DHCP services. This is ideal for when you want to limit or control access to the LAN or internet for an individual subset of users.