UrBackup is designed differently than other backup systems. The “bits” (contents of files) are stored separately from the “metadata” (information about the files, like what you see in the directory listing). This lets UrBackup keep a single copy of the “bits” for files that are saved in multiple places or even on different client computers.
Every full or incremental backup updates both the “bits” and “metadata”, combining them into the same thing as a full backup on that date. As far as restoring files goes, which is the reason for backups, there is no difference in UrBackup between full and incremental except the time taken to perform the backup.
Many people perform only incremental backups, letting UrBackup handle the details. The only reason to perform a “Full” backup is to scan all the selected files on the Client computer and verify nothing changed without UrBackup noticing.