Most carbon steel pans tend to be 1% carbon (very similar to a lot of knife steels actually) whereas cast iron tends to be around 3% from what I've read. But I don't think there's really a definition on either of them that says they have to be a specific percentage of carbon content so there can be quite some variation.
Honestly in actual usage the materials behave very similar actually. Only reason you see a difference with cast iron vs carbon steel is that most cast iron pans are thicker than most carbon steel pans and have a rougher finish. But once you make them the same thickness and finish them the same they behave very similar.
Carbon steel isnt legally defined so even when it's used in the way we normally use it here (indicating a non-stainless knife) that still doesn't say much since the carbon content can still differ wildly, easily from 0,5% to 1,5%. Only way to really find out is to know what steel the knife is made of and what the specs of the steel are. Even in Japan you can find knives in a wide variety of steels that behave quite similar.
So yes, high carbon or carbon steel are all very hollow terms simply because they aren't officially defined in any manner. If you really want to start understanding steels and its impact on edges I suggest you go read Larrin Thomas's blog. But that rabbit whole runs pretty deep...