Vestibulo-ocular reflex (VOR) is a reflex eye movement that stabilizes images on the retina during head movement by producing an eye movement in the direction opposite to head movement, thus preserving the image on the center of the visual field. 

Sensory systems code for four aspects of a stimulus; type (modality), intensity, location, and duration.

Certain receptors are sensitive to certain types of stimuli (for example, different mechanoreceptors respond best to different kinds of touch stimuli, like sharp or blunt objects).

Receptors send impulses in certain patterns to send information about the intensity of a stimulus

(for example, how loud a sound is).

The location of the receptor that is stimulated gives the brain information about the location

of the stimulus (for example, stimulating a mechanoreceptor in a finger will send information to

the brain about that finger).

The duration of the stimulus (how long it lasts) is conveyed by firing patterns of receptors.

Vestibular system as typical sensory system reacts to stimulus. But gravitation is constantly

working stimulus, so vertical head coordination becomes constantly working and reflex process.

This is the main physiology difference between vertical head coordination and any other sensory

process that works sometimes