if you mean flash I can explain. The term component is usually applied to swc file which an be integrated into any flash site and customized through special "component viewer" tool. For example you can have static flash site and want to integrate a shopping cart. You get the flash component and integrate it. Recently the classic meaning of this term was affected by some sites that sell flash modules or flash files with some certain functionality. But as it was easier to promote them as "flash components"(there were some generic google traffic for this keyword) they corrupted the term. In fact they sell usual swf files as a rule based on xml data feed. During recent 2 years these 2 terms mixed up and now "flash component" is defacto standard both to swc and swf files.
Hi. I'm assuming you are referring to a CMS. If so, which one? The terms "module" and "component" mean VERY different things depending upon what you're referring to.