Raisins, sultanas and currants look related and can be used in similar dishes. All three are dried grapes.
For one kilo of raisins you need around four to five kilos of grapes. Currants are made from the Korinthiaki grape variety, also known as black currant. The purple-black grapes mainly come from near the Greek port city of Corinth - which is where the name comes from. The slightly sour currants provide more fruitiness and acidity in sweet dishes.