cPanel is the core hosting interface used to communicate with your website hosting service. Unless you are making significant changes, you will very rarely need to log into your cPanel, if ever. The cPanel interface can also be quite dangerous if you don’t know what you are doing. It gives you the power to delete your website in a click – so be careful.
Your CMS is your content management system. An example is WordPress. Think of your website hosting as storing all your website files. These files are secure, but difficult to interact with. A CMS makes these files easy to manipulate and change. When editing your website, you will be making the changes through the CMS WordPress.