So, I am completely new to the gun/rifle world. My boss, who collects guns, has gotten me interested, so here I am. I have a question that I could probably research on Google, but I think you guys would probably explain it in laymen's terms. What are the differences between the AR-15 and a M4? I see pictures of the two and can't really tell much difference. Maybe I am an idiot or maybe I just have no knowledge of rifles. Thank you.