Archive is a method of storing historical data that is not frequently accessed or modified. Archive can reduce the amount of data that needs to be backed up and save bandwidth and storage space. Differential is a method of backing up only the data that has changed since the last full backup. Differential can also save bandwidth and storage space, as well as speed up the backup process. References: CompTIA Server+ Certification Exam Objectives1, page 12 Server Management: Server Hardware Installation and Management2, Module 2, Lesson 5