using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("---Initializer 1---");

        Dictionary<int, string> planets = new Dictionary<int, string> {

            { 1, "Mercury" },

            { 2, "Venus" },

            { 3, "Earth" }

        };

        foreach (var item in planets)

        {

            Console.WriteLine($"{item.Key}, {item.Value}");

        }

        Console.WriteLine("---Initializer 2---");

        var planets2 = new Dictionary<int, Planet> {

            { 101, new Planet() { Id = 1, Name = "Mercury" } },

            { 102, new Planet() { Id = 2, Name = "Venus" } },

            { 103, new Planet() { Id = 3, Name = "Earth" } }

        };

        foreach (var item in planets2)

        {

            Console.WriteLine($"{item.Key}, {item.Value.Id} and {item.Value.Name}");

        }

    }

}

​

public class Planet

{

    public int Id { get; set; }

    public string Name { get; set; }

}