What is the difference between a friend and a follower and how can I return the gesture if someone follows me?

I don't see the point of following someone unless you're interested on their questions or wanted to be friends. Most of my followers never interact with me, so.. Mmnaahh, don't bother if you aren't into it. People can always interact without adding each other if they have sort of interest about each other.
I unfollow those I added wanting to be friend and they don't add me back 😞