What is the difference between an Agile process model and and Agile framework?

From my understanding Agile process model is a generic term that refers to process models that are based on the agile manifesto and rules. Agile process model = a collection of process models. Agile framework is a partially defined agile process model that you can customize to meet your development needs. For example, Scrum and XP are agile frameworks and at the same time agile process models.

Is my understanding correct? Also what is the difference between agile methodology and agile framework?