M2V is a video category file format, also called MPEG-2 Video. It supports video with a tighter time constraint and interlaced display. The encoded speed at which data is transmitted may be of the order of 40 Mbps (for storage and transmission). It may be higher for professional use in video production. Large frame sizes do not support HD resolution. MPEG-2 format is compatible with MPEG-1. The MPEG-2 format is used mainly for the consumer level of video broadcasting - for example, DVB. And for storage - for example, DVD. But they are also used for professional applications. Say for storing video in a studio. Files with the extension .m2v are necessary if you are preparing a video for burning to DVD using specialized programs. There will be no sound in such a file. This encoding method also involves the .m2a file, where the sound is stored. Then this pair of files (.m2v and .m2a) will be sent to the authoring program line. The program will output them without recoding in the program stream (MPEG 2 PS). There is one caveat. When the weight of these files is 4.3 GB or more, then you need to transcode this file and reduce the bitrate. So when you create * .m2v, you must first select the correct bitrate.
AAC is a sound encoded file format developed by Fraunhofer IIS, AT&T, Dolby and Sony. Its name stands for Advanced Audio Coding. The AAC format is an industry standard and was created as an improved alternative to the most common MP3 audio file format. AAC files do have slightly improved features compared to MP3s. Let's say this format provides the opportunity for improved processing of frequencies above 16 kHz. At the same time, the sound quality of AAC files is closer to the original sound source.