www.example.com and example.com are considered as two different sites by Google and other search engines. The main domain is example.com and any other names like www.example.com are considered as a separate subdomains. Hence, you need to be careful and setup proper redirection between www and non- www versions of your site. Otherwise search engines will think the content is duplicated on two different sites and show both sites in search results.

After you setup your preferred version, it is necessary to check the redirection is working fine. Here is a free tool to check the redirection between www and non-www versions of your site is working fine. Simply, enter the domain name and click "Submit" button. The tool will check the redirection and confirm the status. Make sure the status is showing as "Good" indicating the redirection on your site is working fine.