Is it possible to create a user interface without the help of python framework (like tinker or pygame) and use only vanilla python code? If yes, how?
Can you briefly explain how python framework works?
Is the code of different python framework different?
If the computer did not have the framework installed, will the program still runnable if the program uses a framework?
Thanks very much
Yes, after all tinker and pygame are just python classes packaged as modules.
Python frameworks are a bunch of pre-tested and reusable modules that allow you to use and extend upon so you don't have to reinvent the wheel. 
Yes, frameworks will have differences in usability and code.
The computer will always need the dependencies, though you can package these in various ways aka create a package that has all your dependencies for the program to run.
Making GUI with only python without framework?