A dynamic website doesn’t guarantee that the content displayed on it will be dynamic. It has more to do with how the website is built regardless of its content. Dynamic content on the other hand will always be dynamic.
Let’s take e-shops as an example – they’re dynamic websites. If you’re looking for the best sink, the website will make sure to show you the best picks based on general popularity and your filter criteria (if you’re looking for some specific sink).
The difference between a dynamic website and dynamic content here is that all visitors will get the same results for the same filters. Dynamic content in this context would be some personalized deal or suggestion.