Software design patterns represent proven solutions to recurring software design problems. They capture the knowledge of software experts in an easy to learn fashion. Upon learning, they help freshers and the experts to produce high quality software designs with desired properties. Ability to use design patterns is an essentially required skill of any software engineer and represents maturity.
"An enterprise architecture (EA) describes the structure of an enterprise, its decomposition into subsystems, the relationships between the subsystems, the relationships with the external environment, the terminology to use, and the guiding principles for the design and evolution of an enterprise. An enterprise architecture provides a holistic, systematic description of an enterprise. It encompasses business functions, business process, people, organization, business information, software applications and computer systems with their relationships to enterprise goals." - Wikipedia