Duty and tax are just two examples for the sources of income for a government. Duty means levied only on products, first of all, and mainly on goods that are imported from another nation (custom duty), while export duty means the duty imposed on goods that are exported from the country. Taxes, on the other hand, are binding which means that if someone failing to pay them is punishable. Taxes come as direct and indirect tax. Income tax, for example, is a direct tax and VAT is an indirect tax. So duty and tax are different in the sense that the former is applied only on financial transactions, commodities, estates and so on, whereas the latter is primarily levied on both goods and individuals.
