MichaelZed

Not an accurate analogy, because the flac and mp3 may have the same resolution, but the second suffers from compression artifacts. If your friend is a photographer or graphics person, tell them the difference is like a highly-compressed, 15-kB jpeg image file vs. an uncompressed 10-MB RAW or tiff file. Or do a demo. Open a good clean photo in an image-editing program (on a Mac, Preview.app will do). Save a copy as jpeg, and choose a medium-low quality setting, and save another at very low quality. Compare the images to your clean original. See how the low-q jpeg has added colour noise, a checkerboard pattern added in smooth areas, and squiggly artifacts in the sharp details. Then zoom in and see how a medium-quality jpeg may look good at first glance, but actually has the same artifacts. All three files have identical resolution and colour depth, analogous to audio sampling rate, but different file sizes, analogous to different compressed audio bitrates.