time module vs. datetime module: plain language for beginners

[Jinghui Niu]

I am learning python programming. One thing that gives me a lot of confusion is the division of labours between the time module and the datetime module.

As it turns out to be, time module is not only about time, it's about date too. And datetime doesn't natively support timezone, you have to create one for yourself. 

Why duplicate datetime module? What is the design rationale between this division? Can't we just have one unified module that deals with dates and times? Could someone please list some situations where the two modules are actually useful in their own ways respectively?

Explanation with not too much jargon is highly appreciated. Thanks in advance.