Answer:
We can find the difference using the definition of each concept.
First of all, kinematics refer to a subfield of classical mechanics that only DESCRIBES the motion of a body, point or any object.
Now, vehicular kinematics refer to the study of the motion of a vehicule, only to describe the movement. This subject is studied to test vehicules. Vehicular kinematics and vehicule dynamics are two important fields to analyse in vehicules production, to improvement them in case of accidents. It's important to specify that all these studies are only about the car itself.
On the other hand, we have occupant kinematics which refer to the study of the motion of the occupant who is inside the vehicle. This study is aimed to calculate the movement of the occupant in case of accidents, in order to prevent serious injuries. The best example for this is the air bag, which is an invention to prevent major injuries in case of accidents, this innovation was developed by analysing the motion of the occupant to see where the body goes and which part of the body hits the car inside. The air bag represents a simple but useful innovation that prevents many death per year in car accidents.
Therefore, basically, the difference between these two kinematics is that one studies the vehicle motion and the other one studies the occupant motion, the person inside the vehicle. These studies are important to develop and innovate new things to prevent accidents or serious injuries after an accident.
