The capacity to be used, treated, or developed for a specific purpose. Often it refers to A talent or ability that has potential for development or use.
The term capability is typically used in the context of groups and organizations rather than in the context of individuals, and it is future oriented. It refers to a potential of an organization of being able to do something, i.e. to a potential ability.
When used in the context of individuals, capability is a potential ability that the individual can improve. It may also refer to an extreme of ability, e.g. being able to write Wiki articles but having the capability of writing hundred Wiki articles in one day.