Seeing how the two nations are close geographiocally I would say yes they are related. Of course each country has its own unique way of doing the techniques based on its ancestors and culture.
The one thing I do find interesting is that Japanese Karate and Chinese Kung Fu both wear peasant uniforms to workout in. The Chinese wear a kung fu uniform (see it here at www.classickungfuuniforms.com) and the Japanese wear a karate gi (see a video of it here at https://www.youtube.com/watch?v=lRHwJcInqck). I find that very interesting.
It seems that both cultures wore what was on hand. And that was the common clothing of the day.
To see more of the more elaborate clothing worn by these ancient Asian cultures check out this video I found: