CMS or Content Management System is a web application to manage the content (Text, Images, Videos, audios,) of a website. Basically, you can create a website using a CMS without having much knowledge about the web developing languages. It has the drag and drop like features to add the content. WordPress, Joomla, Drupal are some of the most popular CMSs available for web app development. In addition to that, there are a lot of CMS’s templates also available in the market to create a website. Its pre-defined structure will have a pre-defined design (UI/UX) for the website. However, they are very hard coded and a non-developer can face some difficulties if he wants to edit the content over the limits of the template. Even to use a CMS to its optimum level, you need to learn/play around with it a bit first, as it is not that user-friendly like facebook, linkedin, or any other open source app.
So, the best thing one can opt for using a CMS is to get acquainted with the CMS and some good UI/UX techniques. That would help one to create an attractive website according to his/her needs using CMS and without the help of any developers in future. In my quest of understanding CMS and its UI/UX to the core, I have come across a webinar on UI/UX best practices in CMS based web design. I think this would be a perfect fit for you to understand CMS & web designing, and resolve all your quandaries.
Web development is the work involved in developing a website for the Internet or an intranet. Web development can range from developing a simple single static page of plain text to complex web-based internet applications, electronic businesses, and social network services.