CGI server variables or
CGI scope contains variables that are passed from the web server to the CFML server.
The name of the web server / connector used to communicate with the CFML server. Example:
Apache/2.4.16 (Unix) mod_jk/1.2.40
The hostname or IP address of the web server. Typically this is the value of the
Host header sent by the client in the HTTP request.
Adobe CGI Server Variables Documentation: https://helpx.adobe.com/coldfusion/cfml-reference/reserved-words-and-variables/cgi-environment-cgi-scope-variables/cgi-server-variables.html
CGI client variables or
CGI scope also contains variables that are passed from the browser to the CFML server in the request header.
Browser information of the internet browser used by the client. For e.g.
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0
Adobe CGI Client Variables Documentation: https://helpx.adobe.com/coldfusion/cfml-reference/reserved-words-and-variables/cgi-environment-cgi-scope-variables/cgi-client-variables.html