What is the difference between OnSubjobOK and OnComponentOK?

OnSubjobOK and OnComponentOK are trigger links, which can link to another subjob. 

The main difference between OnSubjobOK and OnComponentOK lies in the execution order of the linked subjob. With OnSubjobOK, the linked subjob starts only when the previous subjob completely finishes. With OnComponentOK, the linked subjob starts when the previous component finishes.