SQL Server on Azure Virtual Machines

Direct access to the OS: Provides additional control over the Operating System patching, the SQL Server patching, the networking and storage configurations on the Virtual Machine.
It uses Azure VM and is similar to the on-premise SQL Server
Supports all features and compatibly with SQL Server
The hardware, software configuration and maintenance are provided by Azure and users maintain OS and applications.
Deployment Options depending on the cost and granular control over the underlying platform.
Allows database professionals to use the full SQL Server version in Azure infrastructure without managing the on-premise hardware.
Use native SQL Server solutions such as SSAS, SSRS, SSIS. Machine-learning ( R, Python)
A legacy application running on older SQL Server versions.
Application compatibility and feature restrictions

Pay-As-You-Go: For paying pay-per-minute for the use of SQL Server which includes the cost of the virtual machine. A user selects an image from the Azure Marketplace and uses a pre-configured VM with SQL Server installed. A user uses this method irrespective of whether you are participating in the Microsoft Software Assurance (SA) program or not.
BYOL (Bring Your Own License): It requires a valid SQL Server license which users apply to Azure VM. A user manually installs and configure a SQL Server similar to the on-premise.
Azure Hybrid Benefits( AHB): Significantly reduces the cost of running the Azure cloud. In this model, a user uses an on-premise software assurance to activate SQL Server and Windows licenses on the Azure cloud. It is applicable for RedHat and SUSE subscriptions as well. It applies SQL Server 1 to 4 vCPUs exchange.