Genshin doesn't have enough end game or challenge(spiral abyss isn't enough) and is just a 150hr sp game that's free but makes you pay for new characters(classes basically).
NGS is tech demo with basically nothing at all to do, but gives you all combat power. classes and skills for free.
Can't compare, but NGS overall is an incomplete shallow sad pathetic excuse for a "game", while Genshin provides enough gameplay to ACTUALLY be considered a video game.
Both are terrible always online games and fail at being "live service" games, though.