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.
ASF is a media file format developed by Microsoft. This format is preferred for Windows Media. This player can play not only video or audio files, but also mixed recordings that are compressed using certain codecs and saved in an ASF file. Files of this format also additionally store metadata (including title, author, copyright information). The full original name of the format is Advanced Systems Format. The main goal of Microsoft in developing this format was to provide streaming media playback.