If there is reassignment, passing a reference type with ref changes the behaviour, e.g.:

    static void ReassignArray(int[] arr)
    {
        arr = new int[] { 99, 98, 97 }; // This reassignment does not affect the original array 
    }

    static void ReassignArrayWithRef(ref int[] arr)
    {
        arr = new int[] { 99, 98, 97 }; // This reassignment affects the original array
    }

However, is there a difference when changing the object directly:

    static void ChangeFirst(int[] arr) {
        arr[0] = 4;  // will affect the original array
    }
    
    static void ChangeFirst(ref int[] arr) {
        arr[0] = 6;  // will affec the original array
    }

Apart from obvious performance gains for the method with the ref keyword, is there a difference when there is no reassignment?