Honestly I don't even know the difference between them lmao
Basically there are huge overlaps. Mythological both Karate and Kung fo originate from Darum / India who is no one else then Bodidharma the founder of Chàn in China and Zen Buddhism in Japan.
If you look about historical facts especially Okinawan Karate styles originate within chinese Kenpo. There was a strong cultural connection with esp. Fujian province during Ming dynasty era and later on.
Lots of chinese people moved to Okinawa and brought their style of fighting. Shorin Ryu / Shuri Te can even be translated as Kung Fu to chinese. As weapons were forbidden on Okinawa ( Shimazu 1609 on) in that time frame
Okinawan styles stayed true to their origin and in my opinion nowadays some Okinawan styles are a lot closer to the original Kung Fu styles as White Crane Fujian then anything in China.
Thats why to this day near any Okinawan style on Okinawa does also full contact sparring. This is meant to fight and thats its spiritual foundation.
In the end if you really use a martial art to fight weaponless there are only certain ways and they all focus on knee, leg, fist punch, ellbow and head as weapons.
Chinas cultural revolution or better culttural elimination surpressed and destroyed martial arts foundations. Thats why they had to reinvent by lore and thats imo why its often so detached from real fight application and sometimes feels like a fairy tale.
What is shown today and trained in temples in China ( what I have seen) I would more call folklore artistic dancing and kind of detached from its origins version of Kung Fu. All the "it should not be trained as full contact or even semi contact sparring / competition" originates from this detachement through Mao.
Kung Fu as a fighting art had many different styles that are lost nowadays. The ones we know of were not much different if at all to Okinawan Karate and as that hasnt changed much you can study that up to today in Japan.
Its all changing again nowdays as China opens up and Sanda is allowed and MT and boxing are also possible to train.