People often associate karate with the stance where the majority of weight is on the front leg, with front leg bent and back leg straight; and people often asociate kung fu with the stance where most or all of the weight is on the rear leg. People often even say that karate and kung fu are a world apart.
In reality, both karate and kung fu use all types of stances.
And the only major difference between the stance with the weight on the back leg, and the stance with the weight on the front leg, is the position of the back leg. The front leg, front hand and upper torso stay in about the same position between both stances.
Karate literally means “empty-handed” and kung fu means “hard work”, so if you’re working hard in practicing empty-handed combat, then you’re doing both karate and kung fu.