OnSubjobOK and OnComponentOK are trigger links, which can link to another subjob. The main difference between them lies in the execution order of the linked subjob.
A subjob is a self-contained subset of a larger Job, composed of components and links.
The following diagram shows a Job with three subjobs:
The execution order of subjobs linked by OnComponentOK is within the execution cycle of the previous subjob. In this example, subjob 2 starts when tLogRow_1 finishes; subjob 3 starts when both subjob 1 and subjob 2 end, because subjob 2 runs within the execution cycle of subjob 1.
Only the first component of a subjob can use the OnSubjobOK link.