Features of Pro

Provides the capability to control and schedule the windows update.  This enables the policies related to Update such as Update/AllowAutoUpdate, Update/ScheduledInstallDay, Update/ScheduledInstallTime, Update/UpdateServiceUrl.

Preinstall and servicing (updating) of store signed apps.

Requirments of Pro

You must be and OEM. If you are developer wishing, for instance, to preinstall apps for IoT you must seek sponsorship from an OEM enrolled in the program.

Registering as an OEM

We haven't found the way yet!  This seems a good starting point: https://partner.microsoft.com/en-us/solutions/oem-partner-center

Creating Windows IoT Core Pro Device

https://developer.microsoft.com/en-us/windows/iot/docs/createiotcorepro