No each is its own special standard actu
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To clarify this: using Cleave is, indeed, a standard action unto itself; however, to use Vital Strike, you must take the Attack Action, which just so happens to be a specific standard action. This is important to note because certain other abilities also require one to take the Attack Action (such as the Two-Handed Fighter archetype's Overhand Chop ability), which would allow a character to use said ability in conjunction with Vital Strike.
However, Cleaving Finish and Vital Strike go together nicely.