What is the difference between M4A and AAC Audio Files?

Question

is there a difference between M4A audio files and AAC audio files or are they exactly the same thing but with a different file extension ?

Answer 1

They are not the same thing. An m4a is basically the same thing as an mp4, and is just a container format. codec != container. It does not imply a codec, and therefor could contain mp3, ac3 or any other audio codec. A AAC file is concatenated AAC frames prepended with ADTS headers (and optionally an ID3 tag).