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 which support DOC file extensions.
RTFRich Text File Format
Introduced and documented by Microsoft, the Rich Text Format (RTF) represents a method of encoding formatted text and graphics for use within applications. The format facilitates cross-platform document exchange with other Microsoft Products, thus serving the purpose of interoperability. This capability makes it a standard of data transfer between word processing software and, hence, contents can be transferred from one operating system to another without losing document formatting.