Azure Backup is a backup as a service offering that provides protection for physical or virtual machines no matter where they reside—on-premises or in the cloud. Azure Backup encompasses several components (Azure Backup agent, System Center Data Protection Manager [DPM], Azure Backup Server, and Azure Backup [VM extension]) that work together to protect a wide range of servers and workloads.
Azure Backup uses a Recovery Services vault for storing the backup data. A vault is backed by Azure Storage (block) blobs, making it a very efficient and economical long-term storage medium. With the vault in place, you can select the machines to back up and define a backup policy (when snapshots are taken and for how long they’re stored).
Azure Backup can be used for a wide range of data backup scenarios, such as the following:
Files and folders on Windows OS machines (physical or virtual)
Application-aware snapshots (VSS—Volume Shadow Copy Service)
Popular Microsoft server workloads such as Microsoft SQL Server, Microsoft SharePoint, and Microsoft Exchange (via System Center DPM or Azure Backup Server)
Linux support (if hosted on Hyper-V)
Native support for Azure Virtual Machines, both Windows and Linux
Windows 10 client machines
Even though Azure Backup and Azure Site Recovery share the same Azure portal experience, they are different services and have different value propositions. Azure Backup is for the backup and restore of data on-premises and in the cloud—it keeps your data safe and recoverable. Azure Site Recovery is about replication of virtual or physical machines—it keeps your workloads available in an outage.
Source of Information : Microsoft Azure Essentials Fundamentals of Azure Second Edition