Are you confused?
Well, for starters, let me tell you that you would need a CMS based website when you need to updated your website regularly. Now, what's a CMS? It stands for Content Management System and there are many software like WordPress, Joomla, Magento, etc. that makes building and managing a website easier. It makes it easier by providing you an administrative dashboard where you can manage t he pages, build new pages, add or remove content, and do all the stuffs like that. So, if you need a website where you will be adding new content regularly, say weekly or daily, a CMS based website is a good go. But that will make our WordPress team happy, but upset our Development Theme. I, being more of a developer, would be the one getting upset.
The basic difference is custom building a website gives us the complete to freedom to design anything, develop anything and keep the complete control to ourselves. Using a CMS gives us ready-made options to use themes and plugins which reduces the development time and cost, but you will sometimes have to compromise with the style and features provided by them, unless of course you are willing to get all themes and plugins developed according to your requirements.
A custom built website is also more secure (actually depends on efficiency of your developer). It has files only that your website needs, so it uses lesser space on your hosting account. Thus, it keeps your website light and faster to load and reduces your hosting maintenance work.
To sum up, it all depends on the customization you are looking for, the amount you want to spend, and most important, the purpose of your website. We at Dharmishi Technologies, provide both the options. We are equality efficient in putting up your CMS based websites, providing you the best WordPress Development Services and also full customized websites and web apps with our website designing and web development services.