Firebase push() vs Angularfire $save()

How does angularfire .$save() compare to firebase .push()? I know push() will generate a unique key when data is stored, but I can't recreate the behavior using angularfire. Is there a way or should I be using .push() and if so, in what case would you use $save()?

Here is one sample I have using $save()...

        var fb = new Firebase(FIREBASE_URI).child('Test');
        var article = $firebaseObject(fb);

        article.Foo = "bar";
        article.$save().then(function(fb) {
            console.log(fb.key() === article.$id); // true
        }, function(error) {
            console.log("Error:", error);
        });

And another using .push()...

        var article = new Firebase(FIREBASE_URI).child('Articles');

        article.push({
            title:   $scope.article.title,
            post:    $scope.article.post
        }, function(error) {
            if (error) {
                console.log("Error:", error);
            }
        });

What are the Pros/Cons and use cases for both?