A: Some downloads provide the option to choose different formats. This would be noted as such in the description of the item. Free downloads with the purchase of a physical format typically come as an MP3.
Below are the descriptions of the formats. The MP3 format is not high fidelity but unless you consider yourself an audiophile, you may not notice a difference. The MP3 file size is MUCH smaller and quick to download and is more portable due to the smaller size. The lossless files are much larger and are intended for audiophiles.
MP3 (itunes compatible) - This file type uses compression to reduce the amount of data required to represent the audio recording while still sounding like a faithful reproduction of the original uncompressed audio for most listeners. It is a standard audio format for playback of music on digital audio players.
ALAC (itunes compatible) - The Apple Lossless Audio Codec is an audio format developed by Apple for lossless data compression of digital music. Apple Lossless data is stored within an MP4 container with the filename extension .m4a, either in desktop operating systems (Mac OS or Windows) or iOS devices. All current iDevices can play ALAC–encoded files.
FLAC (not compatible in itunes) - The 'Free Lossless Audio Codec' is a format which allows digital audio to be losslessly compressed such that the file size is reduced without any information being lost.
A strength of FLAC, as compared to other lossless formats, is its ability to be decoded quickly to WAV. FLAC uses the fastest and most efficient decoders in the lossless audio format.