Files with ODP extension represents the presentation file format used by OpenOffice.org in the OASIS OpenDocument standard. A presentation file is a collection of slides where each slide can comprise text, images, formatting, animations, and other media. These slides are presented to an audience in the form of slideshows with custom presentation settings.
Files with PPTX extension are presentation files created with popular Microsoft PowerPoint application. Unlike the previous version of presentation file format PPT which was binary, the PPTX format is based on the Microsoft PowerPoint open XML presentation file format. A presentation file is a collection of slides where each slide can comprise of text, images, formatting, animations, and other media.
You can also convert ODP into many other file formats. Please see the complete list below.