EDB is a file format used by Exchange Server database to stores all its directory, mail and public folder information. This file contains all the user mailboxes data items such as emails, calendar, calendars, attachments, tasks, notes and journals.
All communication that takes place in the organization where Exchange Server is set up is stored in the EDB file. Whereas, PST is also a file format used by MS Outlook that contains a specific user’s mailboxes on the client computer. MS Outlook can also be used as a stand-alone application or work together with the Exchange Server.