A file with an .ai extension is an Adobe Illustrator Artwork file that contains vector graphics on a single page. It uses points to create paths for displaying the image data, thus making it safe from losing image quality if it is enlarged. AI format finds its major usage for logos and print media. AI files can be opened with Adobe Illustrator, Adobe Acrobat DC, PaintShop Pro, and CorelDraw Graphics tools.
A file with PPT extension represents PowerPoint file that consists of a collection of slides for displaying as SlideShow. It specifies the Binary File Format used by Microsoft PowerPoint 97-2003. A PPT file can contain several different types of information such as text, bulleted points, images, multimedia and other embedded OLE objects. Microsoft came up with newer file format for PowerPoint, known as PPTX, from 2007 onwards that is based on Office OpenXML and is different from this binary file format.
You can also convert AI into many other file formats. Please see the complete list below.