SQL SERVER – Difference Between EXEC and EXECUTE vs EXEC()

SQL SERVER – Difference Between EXEC and EXECUTE vs EXEC() – Use EXEC/EXECUTE for SP always

What is the difference between EXEC and EXECUTE?

They are the same. Both of them executes stored procedure when called as
EXEC sp_help
GO
EXECUTE sp_help
GO

I have seen enough times developer getting confused between EXEC and EXEC(). EXEC command executes stored procedure where as EXEC() function takes dynamic string as input and executes them.
EXEC('EXEC sp_help')
GO

Source:  http://blog.sqlauthority.com/2007/09/13/sql-server-difference-between-exec-and-execute-vs-exec-use-execexecute-for-sp-always/