Get difference between two collections with different keys

I have two collections to compare:

$collection1 = collect([
    'alex',
    'john'
]);

$collection2 = collect([
    [
        'id' => 1,
        'name' => 'alex',
    ],
    [
        'id' => 2,
        'name' => 'john',
    ],
    [
        'id' => 3,
        'name' => 'joe',
    ],
]);

I want to compare collection2 with $collection1 and only get items which the name value doesnt in the other collection, the result i want:

[
    'id' => 3,
    'name' => 'joe',
]

But the problem is the first collection have flat array so, i did this:

$collection2->diffUsing($collection1, function ($a, $b){
    return strcmp($a['name'], $b);
});

But i get the error :

ErrorException : strcmp() expects parameter 2 to be string, array given