What is the difference between balances[owner] and balances[plot.owner]?

Question

I'm learning Solidity via this https://medium.com/coinmonks/ethereum-land-marketplace-dapp-tutorial-part-1-create-and-deploy-a-smart-contract-351bc0d62be2

There's a function below that I don't know the difference between balances[owner] and balances[plot.owner].

function buyPlot(uint index) public payable {
    Plot storage plot = plots[index];

    require(msg.sender != plot.owner && plot.forSale && msg.value >= plot.price);

    if(plot.owner == 0x0) {
        balances[owner] += msg.value;
    }else {
        balances[plot.owner] += msg.value;
    }

    plot.owner = msg.sender;
    plot.forSale = false;

    emit PlotOwnerChanged(index);
}

Does it mean, if no one owns the plot (where plot.owner == 0x0) then pay the funds to the owner of the smart contract (the creator) or first owner of the land?

Here's the entire code.

pragma solidity ^0.4.11;

contract LandContract {
address owner;
mapping (address => uint) public balances;

struct Plot {
    address owner;
    bool forSale;
    uint price;
}

Plot[12] public plots;

event PlotOwnerChanged(
    uint index
);

event PlotPriceChanged(
    uint index,
    uint price
);

event PlotAvailabilityChanged(
    uint index,
    uint price,
    bool forSale
);

constructor() public {
    owner = msg.sender;
    plots[0].price = 4000;
    plots[0].forSale = true;
    plots[1].price = 4000;
    plots[1].forSale = true;
    plots[2].price = 4000;
    plots[2].forSale = true;
    plots[3].price = 4000;
    plots[3].forSale = true;
    plots[4].price = 4000;
    plots[4].forSale = true;
    plots[5].price = 4000;
    plots[5].forSale = true;
    plots[6].price = 4000;
    plots[6].forSale = true;
    plots[7].price = 4000;
    plots[7].forSale = true;
    plots[8].price = 4000;
    plots[8].forSale = true;
    plots[9].price = 4000;
    plots[9].forSale = true;
    plots[10].price = 4000;
    plots[10].forSale = true;
    plots[11].price = 4000;
    plots[11].forSale = true;

}

function putPlotUpForSale(uint index, uint price) public {
    Plot storage plot = plots[index];

    require(msg.sender == plot.owner && price > 0);

    plot.forSale = true;
    plot.price = price;
    emit PlotAvailabilityChanged(index, price, true);
}

function takeOffMarket(uint index) public {
    Plot storage plot = plots[index];

    require(msg.sender == plot.owner);

    plot.forSale = false;
    emit PlotAvailabilityChanged(index, plot.price, false);
}

function getPlots() public view returns(address[], bool[], uint[]) {
    address[] memory addrs = new address[](12);
    bool[] memory available = new bool[](12);
    uint[] memory price = new uint[](12);

    for (uint i = 0; i < 12; i++) {
        Plot storage plot = plots[i];
        addrs[i] = plot.owner;
        price[i] = plot.price;
        available[i] = plot.forSale;
    }

    return (addrs, available, price);
}

function buyPlot(uint index) public payable {
    Plot storage plot = plots[index];

    require(msg.sender != plot.owner && plot.forSale && msg.value >= plot.price);

    if(plot.owner == 0x0) {
        balances[owner] += msg.value;
    }else {
        balances[plot.owner] += msg.value;
    }

    plot.owner = msg.sender;
    plot.forSale = false;

    emit PlotOwnerChanged(index);
}

function withdrawFunds() public {
    address payee = msg.sender;
      uint payment = balances[payee];

      require(payment > 0);

      balances[payee] = 0;
      require(payee.send(payment));
}


function destroy() payable public {
    require(msg.sender == owner);
    selfdestruct(owner);
}
}

Answer 1

Yes, plot.owner is the person who owns a plot. Whereas the owner is the person who deployed the contract. You could think of it as if any plot that has not been bought yet belongs to the owner, that is the person who deployed the contract (assuming he did not transfer the ownership to anyone else), so when you buy a property that was not previously owned by anyone then the money will go to the owner of the contract