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.
SVG files are Scalable Vector Graphics Files that use XML based text format for describing the appearance of image. The word Scalable refers to the fact that the SVG can be scaled to different sizes without losing any quality. Text based description of such files make them independent of resolution. It is one of the mostly used format for building website and print graphics in order to achieve scalability.
You can also convert AI into many other file formats. Please see the complete list below.