What is helper function in python and what is difference between helper function and handler in event driven programming?
The term "helper function" has no official definition. It is just a function that helps or assists other functions.
A "handler" is a callable object (a function for example) that is registered to an event. If that event is triggered, the handler will get called automatically.
You did not give any code and did not name any framework, so I can give this overview without examples only. The implementation differs on the frameworks / libraries used.