@Rajesh Swarnkar Thank you for reaching out to us on Microsoft Q&A community platform. Happy to help!
Cost Management is a set of FinOps tools that enable you to analyze, manage, and optimize your costs. Billing provides all the tools you need to manage your billing account and pay invoices. In other words, Cost Management is used to monitor and control Azure spending and to optimize Azure resource use, while Billing is used to manage your billing account and pay invoices.
Reference document - https://learn.microsoft.com/en-us/azure/cost-management-billing/cost-management-billing-overview
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