Entity relationship (ER) modeling and dimensional modeling (DM) are different logical design techniques. ER modeling seeks to eliminate data redundancy and shows relationships between data, while DM presents data in a standard framework that allows for high performance access. The key differences are that ER modeling contains both logical and physical models, processes normalized data for online transaction processing databases, uses current data with many users, and has smaller and volatile storage, while DM contains only a physical model, processes denormalized data for data warehousing, uses historical data for top management, and has larger and non-volatile storage.