It may have a lower bitrate when compressed. As i understand it on playback of a lossless file it is unpacking of what it needs to play on the fly. So the bitrate on playback is the exact same as the original wave file.
Also the unpacked lossless file is identical to bit, bitrate and frequency for the whole file when analyzed. It would have to be the exact same for the industry to use it, or you would now have rubbish sounding quality cds [freq quality, not the music genre]