Design patterns represent frequently used ways to combine classes or associate objects to achieve a certain purpose. An architectural pattern or a framework provides a skeleton of an overall system architecture. They are based on design patterns. In the existing catalogs of either design patterns or frameworks, numerous are very analogous. They show little differences essentially because they have been developed and used by different people and applications. Therefore, it is really very difficult to choose a pattern. In general, the criteria given for selection are based on examples or case studies. Formalizing the characteristics of the patterns provides the user with more precise criteria of comparison. A relation of specialization can be defined to specify when a pattern can be replaced by another one. To do so, the latter must satisfy the characteristics of the former.