function objectDifferences(object_a, object_b) {

	var differences = [];

	for(var key in object_a) {

		var value = object_a[key];

		if(value != object_b[key])
			differences[key] = object_b[key];

	}

	return differences;

}

var object_a = {apple:'grannysmith', car:'saab', animal:'aardvark'};
var object_b = {apple:'grannysmith', car:'volvo', animal:'panda'};

var differences = objectDifferences(object_a, object_b);

for(var key in differences)
	console.log('found a difference, ' + key + ' in object_b is ' + differences[key]);