SSMS versus SQL Operations Studio

SSMS vs SQLOpsStudio:

SQL Operations Studio (preview) is a free lightweight database development and operations tool that runs on your desktop and is available for Windows, macOS, and Linux. SQL Operations Studio (preview) has built-in support for Azure SQL Database, Azure SQL Data Warehouse, and SQL Server running on-premises or in any cloud. 

SQL Operations Studio (preview) offers a consistent experience across databases of your choice on your favorite operating systems.

SQL Server Management Studio is a fully featured database management tool that enables most DBA’s tasks. It will continue to be the flagship tool with the data tools portfolio. 
SQL Operations Studio enables most of the routine DBA tasks for development and operations of a database but does not have all of the functionality of SSMS. 
SQL Operations Studio is meant to be light weight and easy to use for non-professional DBAs and thus will most likely always optimize usability and light weight to addressing all corner cases.

Investments in flagship Windows tools (SSMS, SSDT, PowerShell) will continue in addition to the next generation of multi-OS and multi-DB CLI and GUI tools. 

The goal is to offer customers the choice of using the tools they want on the platforms of their choice for their scenarios.

Source: https://docs.microsoft.com/en-us/sql/sql-operations-studio/faq