It's helpful to know the following definitions as you begin your Azure cloud journey:
Azure AD tenant: A dedicated and trusted instance of Azure AD. An Azure AD tenant is automatically created when your organization first signs up for a Microsoft cloud service subscription like Microsoft Azure, Intune, or Microsoft 365. An Azure tenant represents a single organization.
Management groups: Logical containers that you use for one or more subscriptions. You can define a hierarchy of management groups, subscriptions, resource groups, and resources to efficiently manage access, policies, and compliance through inheritance.
Subscription: A logical container for your resources. Each Azure resource is associated with only one subscription. Creating a subscription is the first step in adopting Azure.
Resource groups: Logical containers that you use to group related resources in a subscription. Each resource can exist in only one resource group.
Resource groups allow for more granular grouping within a subscription, and are commonly used to represent a collection of assets required to support a workload, application, or specific function within a subscription.
Resource: An entity that's managed by Azure. Examples include Azure Virtual Machines, virtual networks, and storage accounts.
Azure account: The email address that you provide when you create an Azure subscription is the Azure account for the subscription. The party that's associated with the email account is responsible for the monthly costs that are incurred by the resources in the subscription. When you create an Azure account, you provide contact information and billing details, like a credit card. You can use the same Azure account (email address) for multiple subscriptions. Each subscription is associated with only one Azure account.
Account administrator: The party associated with the email address that's used to create an Azure subscription. The account administrator is responsible for paying for all costs that are incurred by the subscription's resources.
Azure Active Directory (Azure AD): The Microsoft cloud-based identity and access management service. Azure AD allows your employees to sign in and access resources.
Azure AD directory: Each Azure AD tenant has a single, dedicated, and trusted directory. The directory includes the tenant's users, groups, and applications. The directory is used to perform identity and access management functions for tenant resources. A directory can be associated with multiple subscriptions, but each subscription is associated with only one directory.
Region: A set of Azure datacenters that are deployed inside a latency-defined perimeter. The datacenters are connected through a dedicated, regional, low-latency network. Most Azure resources run in a specific Azure region.
Link - https://docs.microsoft.com/en-us/