Personas
A persona is the capacity an access is granted in: client contact, supplier, consultant.
Personas live under Access, because they are only used at the moment access is granted. Without at least one, no access can be handed out, which is why new workspaces get two from the start.
You can change the name. You cannot change the key, and that is deliberate: the key is what accesses and apps refer to, and if it changes they both point somewhere wrong without anyone getting an error. While you are creating a persona the key follows the name, until you edit it yourself.
The portal's built-in roles sit read-only on the same page. A role is a set of permissions, a persona is a kind of recipient. The two are not the same thing.