AC3 or Dolby AC-3 is a data format file where six audio channels are compressed by the AC3 codec, also known as Audio Codec 3. The AC3 format is used for the following audio formats - DVD, Blu-ray, cinemas and game consoles. To play the full surround sound of the AC3 file signal, you need a device that supports Dolby Digital technology.
WMA is an abbreviation of Windows Media Audio. The WMA format is designed by Microsoft as an alternative to MP3. The WMA format is characterized by good compression ability and competes with the audio format from Apple AAC. This file format is supported by many portable audio players like the most widespread and common MP3.