The previous version of Azure AD was Windows Active Directory (AD). Active Directory (AD) is an operating system directory service that allows for the unified management of interconnected, complex, and diverse network resources. The main disadvantage of Windows AD was that it had many layers that did different tasks. These layers are as follows:

Upskilling and staying current in the workplace require a Azure Course.

Windows Active Directory Domain Services (ADDS)
ADDS enables the administrator to manage information such as user logins and other details.

ADLS stands for Azure Data Lake Storage Services.
This layer enables the storage of data of any type or size.

ADFS stands for Active Directory Federation Services.
This layer enables you to sign up for all systems and applications with a single click.

ADCS