Following words copyed from Python documentation

__name__

The __name__ attribute must be set to the fully-qualified name of the module. This name is used to uniquely identify the module in the import system.

__main__

__main__ is the name of the scope in which top-level code executes. A module’s __name__ is set equal to '__main__' when read from standard input, a script, or from an interactive prompt.

A module can discover whether or not it is running in the main scope by checking its own __name__, which allows a common idiom for conditionally executing code in a module when it is run as a script or with python -m but not when it is imported:

if __name__ == "__main__":
# execute only if run as a script
main()