wordpress url with www and without www

Hi,

I am facing a problem, My wordpress installation url showing some strange behaviour.

In general setting wordpress address url is set as https://www.example.com
,site address url is set as https://www.example.com and static front page is set as “your latest post”.

We have customized themes index.php which is currently visible at https://www.example.com that is fine.

Now my problem is when someone enter https://example.com rather than https://www.example.com in browser, it showing a blog listing page (your latest post).

Can someone please explain what is wrong and how we can take care of this.

Thanks