SXW is a text file format. From the very beginning, it was created for StarOffice Writer, that is, an application that processes texts from the Sun Microsystem StarOffice office suite. StarOffice was developed by Sun Microsystems. Then it was bought by Oracle. That's why Star Office has evolved into Apache Open Office, and is now a commercial Oracle product. At the same time, it is the same software product as the free program OpenOffice.org. The only difference is that the new Open Office provides technical support for packages. The Apache Software Foundation supports the Apache OpenOffice software package, and it provides a universal set of tools designed to work with vector drawings, spreadsheets, text documents, databases, etc. The .sxw file is an OpenOffice text document that is saved in XML-based Sun XML Writer (SXW) format. Currently, the SXW format and other OpenOffice formats that are outdated have skipped ahead of the family of standard OpenDocument Format (ODF) formats with .odt extensions without preserving compatibility between them. SXW files are opened by programs such as StarOffice Writer and OpenOffice.org Writer.
PPTX is a more modern and convenient presentation format in the popular Power Point application, which replaced PPT after entering the Microsoft PowerPoint 2007 market in updated office suites. Full name - Microsoft PowerPoint Open XML Document. Designed for the same purposes as PPT - creating a presentation in an editable slide show format. The difference from the first version is that the PPTX file is created using the open XML format. If in the PPT format the data is stored in one binary file, then in the PPTX format - in a compressed ZIP archive as a collection of separate files.