Discussion , need one and half page response

Use Case Description versus Activity Diagram"  Please respond to the following:

·       Compare a use case description and an activity diagram. Devise a scenario in which you would use a case description, and devise a scenario in which you would use an activity diagram.

·       Consider a system needed to store information about computers in a computer lab at a university, such as the features and location of each computer. Ascertain the domain classes that might be included within the domain model. Discuss whether or not you believe an entity-relationship diagram (ERD) would be a suitable model.