Motion sickness is a very common disturbance of the inner ear that is caused by repeated motion such as from the swell of the sea, the movement of a car, the motion of a plane in turbulent air, etc. In the inner ear (which is also called the labyrinth), motion sickness affects the sense of balance and equilibrium and, hence, the sense of spatial orientation.
The symptoms of motion sickness include nausea, vomiting, and dizziness (vertigo). Other common signs are sweating and a general feeling of discomfort and not feeling well (malaise).
There is no difference between motion sickness and sea sickness. Some people experience nausea and even vomiting when riding in an airplane, automobile, or amusement park ride. This condition is generally called motion sickness. Many people experience motion sickness when riding on a boat or ship. This is commonly referred to as sea sickness (mal de mer), even though it is the same disorder. They are one and the same phenomenon and will subsequently be referred to as motion sickness.