All these file types are lossless file formats. These files are compressed in a way that reduces the size of the file but does not cause a decrease in audio quality. Standard FLAC & ALAC files are 16-bit with a sample rate of 44.1 KHz.
FLAC-HD & ALAC-HD files are 24-bit. Sample rates vary based on source material and include 44.1 KHz, 48 KHz, 88 KHz and 96 KHz.