The main Difference Between Vatican City and Holy See is
Vatican City state is Refereed as Holy see. Holy see is their Jurisdiction whereas Vatican City is their Geographical Territory. Holy See is equivalent to East India Company – the Vatican is their place for the government in our case Great Britain is the place for East India Company.
Holy See will be headed by a King and Vatican will be headed by Pope. King and Pope is the same person.
Holy See is the only entity which has Absolute Monarchy, King is not hereditary, King is selected by democracy.
Citizens of Vatican are only male and no citizens by birth. Citizenship only if Pope thinks worthy to award.