Specific Jobs and Careers: What is the difference between "VP of Marketing" and "Head of Marketing" in a start-up?

On your resume, you were never a "Head of Marketing" (which to me is the CMO role by definition and not a Director role) but a VP or a CMO. As long as the CEO and HR confirms that, and you had a choice of titles anyway, there should be no problems. I'd claim the CMO title if I were you, but I am just an ambitious American. ;)

My experience in the valley suggests that early stage startups use the title "Head of X" as a hedge. They may be unsure whether the hire in question is the right fit for the actual VP role and want to leave their options open to hire someone in over the existing "Head" if things don't work out well. That way they aren't forced to boot the existing person out of the company to hire in the new VP - and they likely did not have to give up the same level of comp. I've seen an existing "Head" have someone hired in above them, and I've also seen people transition from "Head" to VP. Were I asked this question, I would choose the VP title and the flexibility in terms of comp negotiations, etc. If you look around at more established companies you'll almost never see any "Head of X" titles - you will see VPs & Cxxs.

Depending what your future is this can give you a push in the right direction. Established companies do not have Head of anything the are either VP or SVP. Since you have already broached the situation about changing of your title it should not be a problem. So, when you complete the project then just make the statement that now that you have been with the company and the project is completed you want the title of VP. Don't shy away from this. If they give excuses then I would find some other place of employment. Because, if they do not carry through with their agreement on the changing of title then what else might the not carry through with.Next time either VP or CMO at the start makes things a whole lot easier. But you're knew learn from it and go on with it. We have all made mistakes we wish we could take back but we lived through them.

Vice Presid is a title. Head of Marketing is a description.  Generally, Vice President is at a level of greater authority than a Director; however, organizational structures are as varied as flavors at Baskin Robbins.