Can you clarify the difference you see, if any, between what you understand "ethics" to refer to when used by an average person, and what you understand "peer pressure" to refer to?

Peer pressure is moral in nature if people think of it that way. I can't provide an ontologically basic definition of social morality, but given that you are a human, I'm pretty sure you can identify it when you see it. Pressures within a group that serve to help the group function better are usually moral in nature.