Azure SQL allows you to create and manage your SQL Server resources from a single view, ranging from fully managed PaaS databases to IaaS virtual machines with direct OS and database engine access. All deployment options enable you to bring your on-premises licenses to Azure using Azure Hybrid Benefit.

Databases
Single databases are optimized for modern application development of new cloud-born applications. Databases provide a fully managed SQL experience with extensive and easy to use manageability features.
Includes: single databases, elastic pools, and database servers

Managed instances
Managed instances provide the PaaS benefits of SQL databases with added capabilities that were previously only available in SQL virtual machines. This includes a native virtual network and near 100% compatibility with on-premises SQL Server.
Includes: single instances, instance pools

SQL virtual machines
SQL virtual machines offer an IaaS architecture with extensive control over SQL Server and the underlying OS. Deployments include a management resource that focuses on SQL configuration and enables license updates with no server downtime.
Includes: 60+ available images combining SQL Server 2008-2019 and a variety of available OS and license types