Portal Users are people who have access to the MileWiz Enterprise portal. Depending on the permissions you give them, they can access different sections and teams in the portal. They alone don’t track mileage with that Portal User account. If these portal users need to track mileage as well, they also need to be invited as Drivers as these two are two different types of accounts within the MileWiz system.
Drivers are people who receive an invitation email to install & setup the MileWiz Enterprise app on their smartphone. Once they do that, their trips go to the MileWiz Enterprise portal.
In summary, Portal Users are the people who can access the portal and Drivers are the people who track their trips. One person can be both a Portal User and a Driver but needs to be registered separately for both.