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.
AVI is a video file format developed by Microsoft. The Video for Windows package, within the framework of which the AVI format appeared, was developed by this company in November 1992. It was intended for the operating system Windows 3.1. Since then, for a quarter of a century, the AVI format has remained the main one for storing video files in all versions of Windows operating systems. The name of the format is an abbreviation of the full name Audio Video Interleave File. The format is used to store video data encrypted using a variety of codecs. AVI files, as a rule, use much less compression in comparison with similar formats.