M4V is a video file format developed by Apple for use in its devices, such as iPhones and iPads. It is similar to MP4 but supports additional features like DRM protection and metadata. M4V files are commonly used for movies, TV shows, and videos purchased or downloaded from iTunes.
WMA is a digital audio format developed by Microsoft, primarily used for music and audio streaming. It offers high compression while maintaining good sound quality. WMA files are supported by Windows-based devices and media players, but are less compatible with other operating systems compared to MP3.