Hello Vindeshwar Singh,
Thanks for your question.
Disaster Recovery is suited for simpler, single VM scenarios, whereas Site Recovery in the Recovery Services vault is geared towards more complex and extensive disaster recovery requirements.
Within the Recovery Services vault, you can create a vault which acts as a central location for managing all your disaster recovery configurations and set up replication for multiple VMs, not just one.
See:
https://learn.microsoft.com/en-us/azure/site-recovery/site-recovery-overview
https://learn.microsoft.com/en-us/azure/site-recovery/azure-to-azure-quickstart
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola