What is difference between this

What is difference between this
0

So like

	$('form').on('submit', function(event) {
		$(this).find('span').val();
	});
	$('form').on('submit', function(event) {
		$('span').val();
	});

So have any advantage to use one more better than other? I often read about speed? is have any speed advantage?

Thank you?