The terms are pretty much interchangeable, that is, guns with locks go by several names which share the basic function of using some sort of lock mechanism to ignite gunpowder. The muskets in 'Sharpe's Tiger' are flintlock muskets. Wheelocks and flintlocks, and earlier designs, were all 'firelocks'. Another name for that type of firearm was 'fusil', as in 'King's Fusileers'.
Firelocks and fusils.
Have a culture that is based on an advanced Hellenic setting, you could call it 'Fusils and Falcatas'.
