Question: What's the difference between a peer and a miner?

[rampatra]

I am a bit confused between peers and miners. I know that peers are the ones which have the entire blockchain with them and whenever a new block comes, it is broadcast to all peers, and the peers check the validity and finally add it to the blockchain.

Now I am confused as to who introduces the new block? I see the code which adds a new block which then gets broadcast to all peers but what I do not understand is, who calls the mineCommand()?

function mineCommand(vorpal) {
  vorpal
    .command('mine <data>', 'Mine a new block. Eg: mine hello!')
    .alias('m')
    .action(function(args, callback) {
      if (args.data) {
        blockchain.mine(args.data);
        p2p.broadcastLatest(); 
      }
      callback();
    })
}

From the UI, I get an impression that a peer is the one adding a new block but from the code it doesn't seem so.

[gauravsquadx]

Each peer has only one miner. Miners from all the nodes in a blockchain compete with each other for validating a block (Proof of work).