What is a factory function?

I understand that this question may be considered broad. I am currently learning Javascript and throughout the process I’ve stumbled upon different terms of functions that are thrown around such as: factory function, and constructor functions regarding to object-oriented programming. I am having trouble understanding these terms and finding the distinction among them, although based upon my personal understanding; factory functions are basically regular functions, or am I not seeing the bigger picture in all this? Anyways I hope my brief description of this concept can somehow help in some sort of way.