In some cases the user might install the SQL Server Express Edition, before a “real” SQL Server (e.g. Developer Edition).
This can result in a basic version of Management Studio.
Keep in mind, that with SSMSE (e = Express), you cannot manage Analysis Services, Integration Services, or Reporting Services.
The more, you cannot update the full-text catalog by using SSMSE and it does not support scheduling administrative tasks by using SQL Server Agent.
If you later install a Developer Edition of a SQL Server on your system, you also cannot upgrade from the basic version SSMSE. Only possible thing is, to uninstall SQL Express, and do a “Upgrade” with the Developer Edition SQL Setup to the full version SSMS.
Easiest way to discover SSMSE: try to connect to a SQL server: if your only choice is “database engine”, that’s express .