Adjusting the height of a div to match that of another column
You can save $(this).closest('.papers.left') into a local variable since you access it twice. This might improve performance. It can also enhance code readability:

$('img').each(function () {
    var parent = $(this).closest('.papers.left');
    if (parent.length)
    {
        $(this).on('load', function () {
            $(this).closest('.row').find('.papers.right').height(parent.height());
        })
    }
})




As an add on to your code modification, I don't know that this is faster, but why not try assigning max height to both without checking which is taller? Something like:

$('img').each(function () {
    var parent = $(this).closest('.papers.left');
    if (parent.length)
    {
        $(this).on('load', function () {
            var sibling = $(this).closest('.row').find('.papers.right');
            var height = Math.max(parent.height(), sibling.height());
            parent.height(height);
            sibling.height(height);
        })
    }


})

It's certainly shorter and more readable. Why not test it out to see how the efficiency compares?