The Verge:

When a song is compressed, an algorithm removes bits from the track that it believes the human ear can’t pick up, which reduces the overall file size. So objectively speaking, there’s less audio there for your ear to interpret. Lossless audio cuts less bits.

But in actuality, the difference is very difficult to discern. Couple that with a range in the quality of soundcards and speakers, and it’s almost impossible for the average listener to pick which is which. Can you tell the difference?

Jim posted about this back in March but now Spotify has posted an actual audio test for you to try to see if you can actually hear the difference.