Portable Document Format (PDF) is a type of document created by Adobe back in 1990s. The purpose of this file format was to introduce a standard for representation of documents and other reference material in a format that is independent of application software, hardware as well as Operating System. PDF files can be opened in Adobe Acrobat Reader/Writer as well in most modern browsers like Chrome, Safari, Firefox via extensions/plug-ins.
DOCXMicrosoft Word Open XML Document
Docx is well-known format for Microsoft Word documents. Introduced from 2007 with the release of Microsoft Office 2007, the structure of this new Document format was changed from plain binary to a combination of XML and binary files. Docx files can be opened with Word 2007 and lateral versions but not with the earlier versions of MS Word.