# diffUsing()
The diffUsing method compares the collection against another collection or a plain array based on its values using a callback. This method will return the values in the original collection that are not present in the given collection:
const collection = collect([
{ name: 'Alice', age: 25 },
{ name: 'Bob', age: 30 },
{ name: 'Charlie', age: 35 },
]);
const users = [
{ name: 'Bob', age: 30 },
{ name: 'Charlie', age: 35 },
{ name: 'David', age: 40 },
];
const diff = collection.diffUsing(users, (a, b) => a.age - b.age);
diff.all();
// [{ name: 'Alice', age: 25 }]