Files with .PST extension represent Outlook Personal Storage Files (also called Personal Storage Table) that store variety of user information. User information is stored in folders of different types that include emails, calendar items, notes, contacts, and several other file formats. PST files are used for archiving emailing data offline that can be later loaded and viewed in various applications.
A Tab-Separated Values (TSV) file format represents data separated with tabs in plain text format. The file format, similar to CSV, is used for organization of data in a structured manner in order to import and export between different applications. The format is primarily used for data import/export and exchange in Spreadsheet applications and databases.
You can also convert PST into many other file formats. Please see the complete list below.