Azure SQL Database vs Microsoft SQL Server

Azure SQL Database is a cloud-native relational database service built on the SQL Server engine and delivered as a fully managed PaaS. Microsoft manages provisioning, patching, backups, monitoring, and high availability. The service supports standard T-SQL and can be accessed through the Azure portal, SQL Server Management Studio, Visual Studio Code's MSSQL extension, and compatible application frameworks. It supports native JSON and REST and GraphQL APIs through Data API builder. Hyperscale independently scales compute and storage and supports scale-out with up to 30 named replicas. For AI application development, it offers native vector search and connections to Azure OpenAI and Azure AI Search. It can connect to Azure Functions and replicate SQL data into Microsoft Fabric for near-real-time querying and analysis. Security and governance include a multilayered approach with Microsoft Defender for SQL; recovery features include disaster recovery and snapshot-based backups. The free offer allows up to 10 General Purpose databases per subscription, each with 100,000 vCore seconds, 32 GB of data, and 32 GB of backup storage monthly. Once limits are reached, a database can auto-pause or remain online with excess use billed at standard rates.

Microsoft SQL Server is a database platform for storing, processing, and securing data, offered with both deployment models and a free plan. Its Database Engine includes replication, full-text search, relational, XML, and JSON data management, as well as Python and R machine-learning services. Integration Services provides graphical tools and programmable objects for moving and transforming data, while PolyBase can query Azure Storage, S3, and ODBC sources. SQL Server 2025 adds vector search, vector embedding generation, text chunking, and DiskANN vector indexing, and integrates with LangChain, Semantic Kernel, Entity Framework Core, Microsoft Azure, and Microsoft Fabric. Microsoft provides downloads for Windows and Linux and a SQL Server container image for Docker. Express is a free entry-level edition for learning and desktop or small server applications; its single Database Engine instance is limited to the lesser of one socket or four cores. Developer editions provide Enterprise or Standard functionality for development and testing, not production. SQL Server 2025 does not support SUSE Linux Enterprise Server.