From this and the few other posts - I would strongly recommend reading the below two resources on user managed vs system managed data:
https://www.esri.com/content/dam/esrisites/en-us/media/whitepaper/data-in-arcgis-user-managed-and-ar...
https://enterprise.arcgis.com/en/portal/latest/use/data-store-items.htm
There are likely some Esri Event videos you could search for detailing more.
To outline it simply, Esri created the ArcGIS Data Store allow for front-end data creation. Think easy, system-managed, non-spatial users, all through the UI. How ArcGIS Online works. Scalable. Here, you do NOT have access to the underlying database.
This is in contrast to user-managed data. i.e. Server referencing registered data locations (folders, file geodatabases, cloud connections, enterprise geodatabases). These allow users to access the data directly. And potentially more functionality, but also more administrative overhead.
It's a great scenario as we now have a range of options and can facilitate ease of access to GIS without having to educate or expose access to databases, servers etc.
When you publish from Pro, it will depend on your selection + if the data location is registered with server, but one of three things will happen:
- The data will be published as a Hosted layer (copied to ArcGIS Data Store)
- The data will remain in its location as a registered, referenced service (registered with ArcGIS Server)
- The data will be copied to ArcGIS Server but NOT hosted (the second option, but the file location is not registered, so the data gets copied)
More on these here:
https://pro.arcgis.com/en/pro-app/latest/help/sharing/overview/introduction-to-sharing-web-layers.ht...