Azure Synapse Analytics service currently (as of 6th May 2020) refers to Azure SQL Data Warehouse, more specifically to "gen2" version of it. Microsoft released in November 2019 in Ignite'19 event the new name "Azure Synapse Analytics" and upcoming features for the service. The new features are currently available only in private preview, but I would assume they will be released in public preview soon. Access to new users to private preview is already closed, even though some Microsoft material still hints that you could apply to it.
You can already find information about the new features in documentation and other materil. The confusing part is that you cannot find them in portal yet if you are not part of the private preview. This makes it really hard for new users currently understand what really is available and what is not.
Good start to information on situation and features of both versions this can be found here:
Microsoft has made the release of this update very confusing. I assume they wanted to communicate early in Ignite'19 that they will have a competitive offering coming. Compared to some other cloud native data warehousing solutions the old version of Azure DW clearly were behind in many areas, e.g. in flexible scalability. The new Synapse Analytics capabilities look good and can bring Microsoft back to lead in this area.