Well, I can only speak based on my two years of experience with our local Chun Kuk Do school in Tucson. Problem is, I've never taken Tang Soo Do, only Taekwondo for a while when I was a kid.
Chun Kuk Do is sort of like Tang Soo Do with a lot of the techniques revised in different ways to make them more relevant for fighting.
No C-steps. Things change from time to time in order to keep the style up-to-date. The Chun Kuk Do of 10 years ago is not the Chun Kuk Do of today. Also, the national board sets teaching requirements and curriculum, which is constantly refreshed. Basically, they have experts for everything, like sparring, forms, striking, etc.
Above Blue belt, sparring is required. Basically, you can't move up without sparring. (point sparring). Grappling is required post-black belt (but encouraged at all times, there's an in-house BJJ teacher). Cross training is encouraged. Also, adults and kids have separate classes and learn slightly different techniques (no crippling strikes for 6-year olds).
The big emphasis is on delivering power at all times. Lots of full force work with pads. Sparring, is supposed to be controlled enough to not hurt someone, but all techniques should be delivered in such a way that they could be followed through with. That said, force is sort of gauged based on who you spar with. I know some people think you have to train full contact all the time, but, I'm 42 years old. I can't get beat up 3 times a week. It's bad enough knocking shin bones and walking into side kicks as it is.
At my school, the instructors are great, which makes me feel good about having my son it in it. There's fighting and competition, but the environment is supportive.
I started at age 40, and I was just starting the path of high cholesterol, too much weight, and core weakness (balance problems, plantar fascitis, etc.) Now, blood work is great, and I'm more flexible, and a lot of problems have just gone away.
Seems to blend traditional Karate with elements from other styles to create a more complete experience.
Hope that helps..
Cheers,