I used to have a green belt in Karate, as a kid!
Karate was brought to Japan in the early 20th century.
Was it? That was a long time ago. It reminds me of the movie Karate Kid!
The Karate Kid features the Gōjū-ryū style of karate.
The style is very difficult to master since it involves a lot of intricate movements.
Gō refers to closed hand techniques or straight linear attacks. jū refers to open hand techniques and circular movements.
Yes sometimes people get confused between the two. Even though as you said, they are quite different!
Both principles come from the "Bubishi" which was a martial arts book used by Okinawan masters in the 19th and 20th centuries.