you can log onto service pages with 2 different accounts. Using a Service Pages account (no license required) the user gets basic functionality of logging and viewing service calls. Thats pretty much all they can do with the SP account
Logging in with a licensed account (named or concurrent) the user has more rights which is considered to be "specalist".
The person categories do not have anything to do with it. It is defined by the type of account that they have and the license that they are assigned