Vector images allow for flexibility - these file types, including EPS, AI and PDF, are constructed using mathematical formulas and are excellent for creating graphics that need to be resized. Logos and brand graphics should be created as a vector so they can be used with smaller items like business cards, but they can also be used on large-scale exhibitions/banners.
Raster images use coloured pixels to form a complete image and must be supplied at 300 DPI at precisely the dimensions needed to eliminate any loss of image or pixelation. Almost all photos found online and in print catalogues are raster images, with common image types including JPEGs, GIFs and PNGs.