Not sure I understand the difference of the return values of the two functions

using Treehouse.Models;

namespace Treehouse.Data
{
    public class VideoGamesRepository
    {
        // TODO Add GetVideoGames method
        public static VideoGame[] GetVideoGames()
        {
            return _videoGames;
        }

        // TODO Add GetVideoGame method
        public static VideoGame GetVideoGame(int id)
        {
            VideoGame returnGame = null;
            foreach(var game in _videoGames)
            {    
                if( game.Id == id)
                {
                    returnGame = game;
                    break;
                }
            }
            return returnGame;
        }

        private static VideoGame[] _videoGames = new VideoGame[]
        {
            new VideoGame()
            {
                Id = 1,
                Title = "Super Mario 64",
                Description = "Super Mario 64 is a 1996 platform video game developed and published by Nintendo for the Nintendo 64.",
                Characters = new string[]
                {
                    "Mario",
                    "Princess Peach",
                    "Bowser",
                    "Toad",
                    "Yoshi"
                },
                Publisher = "Nintendo",
                Favorite = true
            },
            new VideoGame()
            {
                Id = 2,
                Title = "Mario Kart 64",
                Description = "Mario Kart 64 is a 1996 go-kart racing game developed and published by Nintendo for the Nintendo 64 video game console.",
                Characters = new string[]
                {
                    "Mario",
                    "Princess Peach",
                    "Bowser",
                    "Toad",
                    "Yoshi"
                },
                Publisher = "Nintendo",
                Favorite = false
            }
        };
    }
}

namespace Treehouse.Models
{
    // Don't make any changes to this class!
    public class VideoGame
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string[] Characters { get; set; }
        public string Publisher { get; set; }
        public bool Favorite { get; set; }

        public string DisplayText
        {
            get
            {
                return Title + " (" + Publisher + ")";
            }
        }
    }
}