Well I can’t help much but Korean Giant (aka Olympic Asian pear) makes big, apple-shaped, full russet, brown crispy Asian pears, ripe at the end of the season, hanging even after leaf fall, October picking in zone 5.
Raja is an early bearing one, but flowers at the same time as Korean Giant, flowering group 2.
I don’t know much more about them, but fruiting times probably will help you differentiate them.