WAV is a container format for storing a record of a digitized audio stream without any compression. This format was developed by IBM and Microsoft in 1991 and was used in all versions of Windows. As the format uses audio streams without any compression, the files become very large in this format.
Mp3 is the most popular and widespread audio format. It was created by MPEG team in the 90s of the last century. MP3 format provides the quality of sound reproduction, similar to the original sound. The MP3 format is based on a lossless compression algorithm made to reduce the data size. In other words, music streams are compressed and deleted in the format that are somehow similar for listening on devices of common use.