Microsoft SQL Server is relational database management system. As a database server it is a software product with the primary function of storing or retrieving data as requested by other software applications which may run either on the same computer or on other computer across a network.
Oracle is a database commonly used for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database workloads.
PostgreSQL is a relational database management system emphasising on extensible and technical standards compliance. It is designed to handle a range of workloads, from single machine to data warehouse or web service with many concurrent users.
Amazon Redshift is a fully managed, peta-scalable data warehouse service on cloud.
Snowflake is a analytical data warehouse provided as Software-as-a-Service. The snowflake data warehouse uses a new SQL database engine with a unique architecture designed for cloud.