pptm A .pptm extension file is a macro enabled open XML, Microsoft PowerPoint Presentation file. The presentation pages that are termed as slides comprise of text, images, videos, graphs and other components including media files that are required in a presentation. This feature is especially helpful to create presentations for the academic, marketing and business domains where a large amount of content needs to be stored. The advantage of using the .pptm extension as compared to .pptx is that macros can be executed in files with this extension whereas it is not possible to execute macros in .pptx files even if it has macros in it, apart from that both formats have similar features. Microsoft introduced the Open XML format for PowerPoint presentations in 2007 hence files with this extension cannot be opened with previous PowerPoint versions. However, if a Microsoft Compatibility Pack is installed along with the previous versions, it would be possible to open the files with .pptm extension.
pptx The PPTX file format is a proprietary XML based file format developed by Microsoft. It is mostly associated with Microsoft office PowerPoint, a closed source slide show presentation application. It is the default format that succeeded the .ppt filename extension from Microsoft PowerPoint 2007 SP1 onwards and is part of the Office Open XML specification. Documents to be saved in the .pptx format are saved as PowerPoint presentations. Because the pptx file format is part of the larger opendocument XML file format, many non-proprietary applications are able to open files saved with the .pptx filename extension.