We will be adding a lot more detail soon, for now a basic explanation of the differences between Cloud Backup and Cloud Storage.
These systems keep a copy of your data offline, on the server of some web hosting service. You do not access this data on a day to day basis. You only download that data when your local data on your computer, laptop or server gets deleted or corrupted.
These systems provide the main storage of your working files. You do not work / edit a file on your local computer, all editing is done live on the online version of that file.
Two areas of confusion with Cloud Storage:
1. Local Offline Copy
With some systems eg Google Chromebook, a version of each file can be stored on your local computer for offline editing (when you do not have internet access, however as soon as you connect to the internet your local file is uploaded and the primary file is once again on the cloud server.
2. Cloud Storage also includes Backup
Virtually all Cloud Service providers automatically keep backup copies of your data on their own servers. Usually on geographically separate servers to offer extra resilience. Many also offer revision versions. ie each time you edit a document the old version is backed up in case you need to restore it due to some major error on the ‘live document’