I was actually just in a review meeting on quenching. They 2 are pretty different and represent sortof the extremes of knife steels, japanese being very hard, and german being very soft (from a material standpoint)
The japanese are harder brittle phases so you can get a thinner sharper blade but it's again more brittle and harder to sharpen. That's what makes the layered laminated japanese steel so cool was being able to layer and layer the steel to have some of the toughness and hardness combined.
Then the german steel is usually softer thicker tougher steel so it's easier to sharpen but less strong so you have a thicker knife you gotta sharpen more. Less precision, more serviceable
I will say I love my german knives and use them often but the japanese 3 layer gets probably 2-3x as much use.