According to Apple, the audio data in a standard AIFF file is uncompressed pulse-code modulation (PCM). (More specifically, the AIFF format used in Mac OS X is AIFF-C/sowt, which only differs from the original AIFF in byte-order, but is not compressed as the C- suffix might suggest. The name refers to the (compressed) AIFF-C format from which the AIFF-C/sowt format was derived.)
Yep.
The information on a CD is a plain byte stream, recorded as 16-bit unsigned integers in pulse code modulation. An AIFF can also contain the same kind of data (a raw 16-bit PCM bytestream); the difference is that an AIFF file wraps the stream of data up in a package that contains things like a header (which describes how the data are stored, what the byte order is, what the sample rate is, whether or not there's compression, and so on), and breaks the stream up into chunks, where each chunk contains information about how large the chunk is, what kind of chunk it is, and so on.
The music on the CD has no header information, no information about the kind of compression (because there is none) or the kind of sampling (because music CDs are always 44.1kHz 16-bit), and it's just a raw stream of sound bytes with no ordering or chunking.
