FLAC is not an exact copy, only an copy of the disc in waveform would be an exact copy, but FLAC does appear to be a nearly identical copy.
FLAC is like a zipped wave file that can be played. If you zip (compress) a file, then unzip(uncompress) it, it's the same file as the original, same with FLAC. FLAC can just be played with the "unzipping" done on-the-fly.