Quiet vs Shy

I made a new friend at work the other day. He told me he always wanted to talk to me, but that I always seemed so shy. 

You wouldn't know this, but I study during every break I have while I'm at work. It's my own fault - I started studying the muscles way too late in the summer & grad school will not be happy with me. Anyways! The point is, I don't really talk to anyone or say anything. 

I knew I was quiet at work, but his word choice of shy made me think about the difference between being quiet and being shy. 

Also... I like being the quiet one because you learn more. About people's opinions, about social hierarchies, about who loves who, about everything.