Explanation

Microsoft Defender for Identity is a cloud-based security solution that leverages your on-premises Active Directory signals to identify, detect, and investigate advanced threats, compromised identities, and malicious insider actions directed at your organization.

Reference:
https://docs.microsoft.com/en-us/microsoft-365/enterprise/about-microsoft-365-identity?view=o365-worldwide

Reference:
https://docs.microsoft.com/en-us/azure/sentinel/overview