Spartans were way better trained as being royalty who should have been exclusively occupied with warfare in addition to their own propaganda that they were invaders and that the helots would betray them first time they could.

Practicing on live helots, being barred from politics until you were old enough and the puritanism all played into making them the most formidable.

I think that despite spartan losses, they almost always had the edge in the training and morale for the average citizen.

Sparta feels like if the Navy seals lead a state. The Shogunate feels more like a long lived junta with feudalism.