Top differences between Critical Path & Critical Chain?

To understand Critical Chain you must have some idea of Theory of Constraints. The crux of the matter is "A chain is as strong as its weakest link". What is the weakest link in project management plan. You cannot take any chances with critical path because any delay on CP is delay in project. Now the question is how to protect the critical path? We have to understand it as the weakest link and to protect it we need to establish buffers to ensure no project gets delayed due to the delay on critical path. If we add a buffer to the critical path in addition to the project duration, that is an increase in original duration which is not acceptable. We have to create this project from within the critical path without adding anything from outside. If we can tax the critical activities and borrow some time from each critical activity, we can put this accumulated time as buffer and restrain the critical activities to their new reduced duration. This project buffer is not in control of those activities from whom it was borrowed and it is the discretion of project manager now if he wants to allow some additional time to one of these activities in trouble, but as a whole a major portion of buffer is secure and is responsible for providing security to the weakest link, our critical path. This will ensure our project will never be delayed and therefore the chain is now string enough. This is called the critical chain.