JPEGs (Joint Photographic Experts Group) can be either CMYK or RGB color space, but do not support transparency (hence always have a “white box”). A “lossy” bitmap (compression removes details), JPEG sacrifices clarity for small file size.
PNG (Portable Network Graphics) supports only the RGB color space, but supports transparency while retaining a relatively small file size. A “lossless” file type, it is often the preferred choice for bitmaps.
—A&E Corel Columnist