A cloud backup and a cloud-to-cloud backup are two different services. Storing data in the cloud is a great option for protecting against hard-drive crashes, stolen laptop or desktop computers, computer viruses and natural disasters.
Backing up to an external hard drive is faster (and so is restoring your data) but the external drive is just as vulnerable to fire, theft and cataclysmic weather events. If your home or office burns down, your external drive and all your backups go with it.
A cloud backup automatically syncs data of some sort between your computer and the cloud vendor’s data centre. The types of data backed up could include photos, videos and documents. The version on your local hard drive is duplicated in the cloud. The cloud version of the data can usually be accessed from any browser, at any time, provided there is an internet connection.
A cloud-to-cloud backup copies data from one cloud service to another. No local hard drives (i.e. owned by the user) are involved. The data is copied from one cloud application to a separate cloud data centre owned and operated by a different provider.
Cloud-to-cloud backups protect against a systems failure or bankruptcy by a cloud software vendor.
Businesses usually use cloud-to-cloud backups to provide protection for critical web-based applications. These can include email and documents (eg. Google Apps), social media (eg. Twitter, Facebook) and CRMs (eg. Salesforce.com).
Users typically have limited or highly regulated access to their backed up data. The main method of restoring the data is to transfer it back to the original cloud application.