Methinks you may be confusing terms.
All a complete backup measn is the entire drive has been backed up. That can be accomplished in several ways.
An image is a snapshot of what's on the drive or partition you are imaging, sort of like a photo negative. The image is used to recreate the data on the drive, sorta like a photo negative is used to create a print. Windows Backup is an imaging program as other programs like Macrium Reflect. Many people here, including me, prefer Macrium Reflect over Windows Backup.
Cloning is making an exact, bootable (id the clone includes the OS) copy of the original drive or partition. Macrium Reflect is also capable of making clones. Cloning is best used for making a duplicate drive to replace an older drive.
Imaging and cloning are the only ways to create bootable copies of System files (OS and Programs). However, they are inefficient for backing up data since they take up so much room and can take so long. What many people recommend is putting the System files on their owen drive or partition and use imaging to back them up.
Data is best backed up using a folder/file syncing program, such as
FreeFileSync set to mirror mode. A folder/syncing program works by comparing the data on the drive, partition, or selected folders of the source drive with the data on the destination drive (the backup), then copies data on the source drive that is not on the destination data and pastes it to the destination drive and deletes data on the destination drive that is not on the source drive. The result is an essentially exact copy of of the source drive. FreeFileSync can also be set to send deleted files to a versioning folder or drive to protect against accidentally deleted files or files that get corrupted. Since only files that have been added, changed, or deleted are involved in the process, updating a backup takes considerably less time than making a copy of the entire surce drive would take.