Function is the same, and the parts in the tank. The 454 Drake II series came first. The tank and bowl look to be a little bigger than the 776 Drake 2021 bowl and tank.
The 454 was an upgrade to the original 744 Drake, and as the 744 was being replaced, the new 776 got some of the features of the 454.
So, basically, the concurrent existence of 2021-onwards Drake and Drake II is nonsensical? Kind of like if a Honda Accord in black would be called Honda Accord, but a Honda Accord in white would be called Honda Shmacord? Imbecility of the highest order…