You mostly heard about open source. So question is what is open source. Baically Open source refers to that software/application(web,mobile,etc.) ,original source code of that software/application is freely available and e redistributed and modified in any form.
Based on PHP there are so many frameworks and CMS are built.
Question : What is the difference between Frameworks and CMS.
Answer : In simple terms CMS(Content management system) built in tools or plugins with UI, with the help of them we easily manage front end. Where ever Framework is collection of predefined classes or libraries by the help of these classes and libraries we can build application.
Following the is list of Framworks
Following is the list of CMS (Content Management System)