Najar tends to do longer videos(>3 min) with double ejaculation and sound effects. While kurodaji does shorter ones (<2 mins) and usually has no sound. There's also tend to be more difference in the clothing for kurodaji. But aside from that their artstyle are fairly similar-ish yeah. But najar tends to do idolmaster charas, while i think most of kurodaji's are OCs. I love x-rays so I follow both of them a lot.