ODP is one of many formats that were born from the Open Office Project. The project was initiated by Sun Microsystems as an answer to the ever rising demand for free office applications. There are many applications that have bought into this, including KOffice and Neooofice. ODP is used by Open Document Presentation files that are created by the OpenOffice software suite. Open Document Format is XML based and therefore easily portable.
ODP files can be opened and edited on applications whose standards are in conformity to the OpenDocument format. The Impress presentation application that comes with StarOffice from Sun Microsystems (now Oracle) can also render ODP files in a similar fashion to OpenOffice. As it's open source, any user can modify the source code to enhance the application and later on publish their modified copies for public consumption.
Originally developed by Forethought, who Microsoft bought out, PPT is the worlds most popular presentation file format. It is a very powerful tool that you can use to create presentations that include pictures, graphs, text and many other objects. Many businesses and students that have to present something will almost always do their presentation using Microsoft PowerPoint.
A large part of any presentation is how the text enters, appears and exits the screen. Entrance, emphasis, and exit of elements on a slide itself are controlled by what PowerPoint calls Custom Animations Transitions. These can be animated in a variety of ways. For example you can customise the animation to create small story boards by animating pictures to enter, exit or move. With different type of callouts, speech bubbles with edited text can be sent on and off to create speech. The overall design of a presentation can dictate how all the other slides appear and operate, this is called a master slide. Everything from design to the text on the slide can be edited using a primitive outliner.