WAV (or WAVE) is actually the first full-fledged audio format with good sound quality. It was developed quite a few years ago by the joint efforts of Microsoft and IBM. Sometimes this format is even called “Audio for Windows,” because it is the standard for storing audio stream for a traditional Windows desktop computer. Full name - Wave Audio File Format. The short name is derived from the English word wave ("wave"). The peculiarity of this format of digitized audio stream is the lack of compression. WAV files take up too much space, but it is ideal for storing high quality files in their original form.
AU is an audio file format created in Audacity. This is a free cross-platform program designed to edit audio files. AU format (Audio Units) was developed by Sun Microsystems. This format greatly simplifies the task of reliable storage of audio files. An AU file consists of 3 parts: a header (max. 24 bytes), a description block of various sizes, and audio data. The file format is used on computers running the Sun or Unix operating system. However, it opens with other audio players. The AU format uses the logarithmic encoding method, previously very popular on computers running the Sun SPARCstation operating system. Previous sound file formats, in order to reduce the size, used the logarithmic scale of recording samples. Among the representatives of such formats, the Sun AU group of formats, which are still in action, gained great fame. Problems with opening the AU file usually manifest themselves when there are no corresponding applications that would be installed on the PC. Applications that use .AU files are Apple QuickTime Player, Microsoft Windows Media Player, Real Player, Winamp, and other widely used audio players. And this is the vast majority of professional audio editors.