Why VPS has httpdocs and httpsdocs?

I’m supposed to put an website onto a VPS server. The website will utilize SSL. Do I put the files in httpdocs folder or the httpsdocs folder? Why are there two? And what is the purpose of each?

I am only familiar with shared-web-hosting where there is only one public_html folder where you are supposed to put public files.

No, SSL is not installed yet.

I believe that does not matter. HTTPS is yours.
BTW SSL is installed?

It’s not a VPS/shared hosting specific issue with regards to what the web root folder is called, but a configuration specific to the version of apache/linux distro the server is using.
If you have two folders then apache will serve and receive to httpdocs over port 80 unencrypted, and over port 443 encrypted in httpsdocs, simple.

yes, it isn’t a VPS’s feature, it is a configuration of webserver installed, if you would like to use https than you should pay attention to it