WAV, sometimes called WAV, is an audio container format developed by IBM and Microsoft and comes with a .wav filename extension. Unlike popular formats like MP3 and MP4, WAV isn’t a lossy format, so it’s bigger and less popular. WAV files can be opened on various OS platforms via software like Windows Media Player, MPlayer, VLC Media Player, and more.
M4B is an audio filename extension for AAC format, which is developed by Apple Inc. It is mainly used on podcast and audiobook files. Typically, M4B files contain audio and other metadata like images, hyperlinks, and chapter markers. M4B files are DRM copy-protected and can be opened on Apple iTunes and QuickTime Player.