That usually depends on which hand is dominant. The dominant hand will have a stronger and shorter clavicle. So if you're right handed, your right clavicle will be shorter but probably thicker.
No-horses do not have a clavicle.
The human clavicle provides fixing for the pectoral girdle allowing dexterity with the forelimb.
Horses however are more interested in stride length & speed. The...