A scripting language is a programming language that uses an Interpreter to translate its source code. The interpreter reads and executes each line of code one at a time, just like a SCRIPT for a play or an audition, hence the the term "scripting language".
Python uses an interpreter to translate and run its code and that's why it's called a scripting language
A Python script normally can be full of functions that can be imported as a library of functions in other scripts, or a python script can be a command that runs in Rhino.
There is a way to have Python definitions be both a library of functions and a direct command.
The key is to add these statements to the end of the file:
if __name__ == '__main__':
CreateCircle() # Put the a call to the main function in the file