There always confuse between Cloud Sync and Cloud Backup so let has a look of what the different of it.
Cloud Sync (e.g. Dropbox, ICloud Drive, OneDrive, Google Drive)
These services sync folders on your computer or mobile device to folders on other machines or into the cloud, allowing users to work from a folder or directory across devices. Typically these services have tiered pricing, meaning you pay for the amount of data you store with the service, or for tiers of data that you are allowed to use. If there is data loss, sometimes these services even have a version history feature. Of course, only files that are in the synced folders are available to be recovered, resulting in sync services not being able to get back files that were never synced.
The protection its offered is quite limited and is not meant to backup massive amounts of website or system content.
Cloud Backup (e.g. Narrowcloud Cloud Backup)
These services should typically work automatically in the background. The user does not usually need to take any action like setting up and working out of specific folders like with sync services (though some online services do differ and you may want to make sure there are no gotchas, like common directories being excluded by default). Backup services typically back up new or changed data that is on your computer to another location. Before the cloud became an available and popular destination, that location was primarily a CD or an external hard drive, but as cloud storage became more readily available and affordable, quickly it became the most popular offsite storage medium. Typically cloud backup services have fixed pricing, and if there is a system crash or data loss, all backed up data is available for restore. In addition, these services have version history and rollback features in case there is data loss or accidental file deletion.