Yes. It is true that both AIFF and ALAC contain the exact same audio data. The difference between the two file types comes from the way that the files are read [played] by the computer. The AIFF file format is a fully uncompressed audio file, where the ALAC audio file is lossless compressed audio file.

Lossless compressed means that while the ALAC file contains all of the original information of the original AIFF audio file, it has been rewritten in a simplified code [computer language] to save on digital storage space. So with Lossless compression audio formats like ALAC a computer program must uncompress the audio file in real time during playback. Think of this as like trying to read a book but instead it’s in a foreign language that you understand and you still need to translate the language in real time as you’re saying it out-loud which takes extra brain power.

It is true that the computer program can make this translation faster than we could ever hope to read a book, but in increases the power you computer uses due to an increase in computing function than it would take to read the natural AIFF file. This matters because the increased computing, and power usage it takes to read an ALAC file can can create digital interference that can result in some audio degrading [worsening] when compared it to the AIFF file**.

**Please note that to actually hear this difference (should it exist) you would need to have a very high end audio listening set up, and possibly super human hearing.