Hi @ramesh singh ,
the first difference between an Azure Recovery Services Vault (ARSV) and an Azure Backup Vault (ABV) is are the available datasources of each vault.
If you create a new Vault in Azure Backup Center there is a screen that is showing the different available datasources of each vault type:
The second difference is: In an ARSV you can be used for Azure Backup and Azure Site Recovery data. An ABV is for Azure Backup data only.
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Regards
Andreas Baumgarten