Question, why 98s it is worse than 78s vs AKo & suited?

I deduct it is because if straight hits the 9 it can cause a bigger straight to the king doing it T to A or 8 to Q making the villain to Aces. But I want to know if somebody studied this topic deeper and has some more in depth information about this and other hands that typically are not looked at first glance has stronger than other, for example JTs is almost flipping vs AKo being 59-41 aprox.

78s

Thanks.