When my customers get started with Azure, one of the first things that trips them up is the terminology. This is a quick primer of the terms you’ll encounter as you begin your journey.
The Azure enrollment is an Azure usage agreement often tied to an Microsoft Enterprise Agreement. One enrollment = one bill. Under the enrollment you create Azure accounts, subscriptions, and ultimately resources (VMs, storage, DBs).
A tenant is a instance of Azure Activity Directory (AAD). A tenant is similar to a Windows AD domain. Within the AAD you can have users, groups, etc. Each instance of Azure, O365, Dynamics, etc. requires a tenant. These tenants can be shared or you can use a unique instance for each one.
*each subscription can use a separate tenant*
An Azure subscription is the unit where all resources (VMs, DBs, etc.) reside. The this is the highest level in an enrollment that can incur charges. A subscription is equivalent to an AWS account.
see also https://docs.microsoft.com/en-us/office365/enterprise/subscriptions-licenses-accounts-and-tenants-for-microsoft-cloud-offerings