JPEG is the most common file format that we have today especially in photographs due to its good quality to compression ratio. As stated, JPEG is a compressed file format for storing realistic images like photographs or paintings. Raw, on the other hand, is not necessarily a file format. It is simply the output of direct from the sensor written into a file without any processing or compression.
JPEG is an acronym for Joint Photographic Experts Group which standardized the compression in order to reduce the amount of file size while maintaining very minimal loss of quality. A Raw photograph taken from a 5 megapixel camera would also be 5MB while a JPG taken with the same camera would only be around 10 to 40 percent of the size.