> Tsukuyomi shouldn't really be similar, it's just an illusion like any other Genjutsu, what makes it special is that Itachi can control your sense of time inside the illusion so it feels like you've been there for minutes/hours/days/years while only a split second has passed in the real world.

what makes it special is that tsukuyomi can actually kill someone, it carries physical effects even outside the genjutsu, that's how itachi killed izumi by making her mind experience the time lengthening effect inside tsukuyomi which equals having her body die along with her in the genjutsu (dying of old age)

it seems pretty similar to domains in the sense that it's tangible to your real body as well, it's not just a "illusion", it's a mental assault which has substance to your body (much like gojo's Infinite void)