In brief, SQL DW is a fully managed data-warehouse-as-a-service that you can provision in minutes and scale up in seconds. With SQL DW, storage and compute scale independently. You can dynamically deploy, grow, shrink, and even pause compute, allowing for cost savings. Also, SQL DW uses the power and familiarity of T-SQL so you can integrate query results across relational data in your data warehouse and non-relational data in Azure blob storage or Hadoop using PolyBase. SQL DW offers an availability SLA of 99.9%, the only public cloud data warehouse service that offers an availability SLA to customers.
SQL DW uses an elastic massively parallel processing (MPP) architecture built on top of the SQL Server 2016 database engine. It allows you to interactively query and analyze data using existing SQL-based tools and business intelligence applications. It uses column stores for high performance analytics and storage compression, a rich collection of aggregation capabilities of SQL Server, and state of the art query optimization capabilities.