Basically the same kick but few small differences, some from the background Karate + Thai vs just Thai, and some differences from the scoring. Boxing scores higher in kickboxing rules vs traditional Muay Thai, so you typically find yourself at closer range when kicking Dutch style.
One example of good Dutch roundhouse kicks is Mr Perfect, Ernesto Hoost. He was an absolute demon with his low kicks, especially when kicking across the front of the thigh instead of to the side of the leg. He'd load up with nice boxing combos, using his hands and footwork to come across or even to turn his opponent then the angle of the kick would end up coming infront of the target instead of to the side where it's easier to check etc, he'd have a decent chamber come round then extend through the kick. Perfect combo of Karate and Muay Thai. Remy Bonjaski is another good example of piecing together Dutch style roundhouse kicks off combos with the his hands. Peter Aerts too, massive kicks coming from his high chamber up, around, then out, BAM.
They're always going to be similar and you will see lots of crossover depending on the fighter and what's happening in the moment. Dutch style is thought of as Karate + Muay Thai, but it's really more like;
Karate + (Karate+Muay thai) + Muay Thai + Boxing
The original Dutch guys, Jan Plas and the others were from Kyokushin Karate, they went to Japan to train in the new kickboxing style with Kenji Kurosaki. Essentially Japanese Kyokushin went to Thailand and added that knowledge to their Karate to make early Kickboxing. Jan formed Mejiro Gym, added more western boxing, had the famous no pads seminar where give and take training was cemented and suddenly Dutch Kickboxing produced some of the best killers around in no time at all.
