If you need to know if a specific file version is the result of an upload, a restore, or a promote operation, then you can use the revisionDisplayLabel and the version's type to help with that.
1) Restored
If the previous version of the file had the type versions:autodesk.core:Deleted then the file has been restored.
2) Promoted
If the previous version of the file did not have the type versions:autodesk.core:Deleted but one of the earlier versions had the same revisionDisplayLabel then it's been promoted
3) Uploaded
If no earlier version has the same revisionDisplayLabel then it's been uploaded
Note: when looking at the payload of the dm.version.modified webhook event you can only tell if it is an upload or a restore/promote operation - in the case of both promote and restore the custom-metadata section will contain "storm:action": "promote"