A library is simply a collection of functions that you can call in your own code to do certain actions that may otherwise be too difficult/inconvenient to develop on your own. An example of a library could be a collection of mathematical functions that allow you to calculate geometry.
However, a framework is more complex. A framework is collection of code that dictates HOW an application should be built. It is focused on enforcing design patterns specific to the framework. Because of this, frameworks aren't something you can easily add into an existing project, rather, it is something that should be implemented in the beginning stages of development. Frameworks may include their own functions to accomplish common tasks, but they are not the bread and butter like in a library.
Not only are frameworks w
