DOTXWord Open XML Document Template
Files with DOTX extension are template files created by Microsoft Word to have pre-formatted settings for generation of further DOCX files. A template file is created in order to have specific user settings that should be applied to subsequent flies created from these. These settings include page margins, borders, headers, footers, and other page settings. Such templates are used in official documents such as company letterheads and standardized forms.
ODTOpen Document Text
ODT files are type of documents created with word processing applications that are based on OpenDocument Text File format. These are created with word processor applications such as free OpenOffice Writer and can hold content such as text, images, objects and styles. The ODT file is to Writer word processor what the DOCX is to Microsoft Word. Several applications including Google Docs and Google's web-based word processor included with Google Drive can open the ODT files for editing.