Hearing is something you can hear even though you have no intention to hear it. Listening is something you want to hear. (There is intention to hear it) e.g.: I heard a noise. I heard my name being called I listen to music I sat and listened to her talking.

Let me put it this way. I am speaking in front of an audience. There's a lot of people there and I'm pretty sure all of them can hear me. What I'm not sure about is, if they are listening to me. So for me, listening comes with understanding what you heard.

Just to add to the other good answers... listening means paying attention.