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.
Files with PPTM extension are Macro-enabled Presentation files that are created with Microsoft PowerPoint 2007 or higher versions. They are similar to PPTX files with the difference that the lateral can't execute macros though they can contain macros. PPTM files can be edited by opening them in Microsoft PowerPoint and updating the contents. Another similar format is PPSM but it is read-only by default and starts the slideshow when opened. PPTM, like PPTX, contains slides for different presentation elements like text, images, videos, graphs and other related material.
You can also convert PST into many other file formats. Please see the complete list below.