Unlike XCI files (which are dumps of game cartridges), NSP files are generally smaller because they do not contain the padding data found on physical cartridges. When you see "Mario Kart 8 Deluxe NSP," you are looking at the digital installable version of the game.

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Users of custom firmware often use tools like NSC Builder to merge these update files with the base game for easier installation. Official users should simply update via the or by pressing the + button on the game icon and selecting "Software Update". How to Update Mario Kart 8 Deluxe | Nintendo Support