What is the difference between nafaqah (financial support/maintenance) and sadaqah (charity), and is what is given monthly to the aunt who raised the questioner considered nafaqah or sadaqah, in order to ascertain the permissibility of giving Zakat money to her?

"Nafaqah" (financial support) is the money expended, and its obligations are threefold: marital ownership (marriage), ownership of a slave, and kinship. Nafaqah is only obligatory; whatever is given to those for whom nafaqah is not obligatory is considered charity (sadaqah). It is permissible to give zakat to one's paternal aunt if she falls under one of the eight categories mentioned in the verse: "Indeed, [obligatory] charities are only for the poor and the needy, and those who work on [collecting] them, and those whose hearts are to be reconciled, and for [freeing] captives, and for those in debt, and for the cause of Allah, and for the stranded traveler – an obligation [imposed] by Allah. And Allah is Knowing and Wise."