using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var cats = new List<Cat>()

        {

            new Cat { Name = "Lily" },

            new Cat { Name = "Mimi" },

            new Cat { Name = "Oren" },

        };

        var dogs = new List<Dog>()

        {

            new Dog { Name = "Lily" },

            new Dog { Name = "Rocky" },

        };

​

        var exceptCats = cats

                     .Where(cat => !dogs.Any(dog => cat.Age == dog.Age && cat.Name == dog.Name))

                    .ToList();

        FiddleHelper.WriteTable(exceptCats);

    }

}

​

public class Cat

{

    public string Name { get; set; }

    public int Age { get; set; }

}

​

public class Dog

{

    public string Name { get; set; }    

    public int Age { get; set; }

}