the differences you have (the amount) from IL to HB is the same with those from C3 to IL.
for example, in C4 nobles/hero was added, that's a BIG update.
in C5 you got clan skills.
in IL shadow items and augmentations.
on kamael again big updates but for HELLBOUND... pff almost nothing. only instances which will get better features in time.
on gracia 1 vitality is one of the most imp, rest are only updates of the existing stuff.