Code
            int[] ints1= new int[]{1,2,3,4,5};
            int[] ints2 = new int[] { 1, 2, 3, 4, 5,6,7};
            ArrayList List1 = new ArrayList();
            List1.AddRange(ints1);
            ArrayList List2 = new ArrayList();
            List2.AddRange(ints2);
            ArrayList ListView3 = new ArrayList();
            StringBuilder sb = new StringBuilder();
            foreach (int item in List2)
            {
                if (!List1.Contains(item))
                {
                    ListView3.Add(item);
                }
            }

Code

        List<object> list1 = new List<object>();//你的原始排除素材
        List<object> list2 = new List<object>();//你的原始所有素材

        Dictionary<object, object> temp = new Dictionary<object, object>();//用于提速

        //加入提速器
        temp.Clear();
        foreach (object o in list1) {
            temp.Add(o, null);
        }

        System.Windows.Forms.ListView listview = new System.Windows.Forms.ListView();//你的目标控件
        foreach (object o in list2) {
            if (!temp.ContainsKey(o))
                listview.Items.Add(new System.Windows.Forms.ListViewItem(new string[] { o.ToString() }));//注意 ListView 的实际列数. 如果两列就用 new string[]{o.ToString(), others} 等
        }