What is the difference between sultanas and raisins?

Along with currants, they're all dried grapes: only different varieties of grapes and using different drying techniques, with or without "drying solutions." These grape varieties often vary depending on particular geographic regions. Some authorities note that sultanas are generally produced from seedless grapes.

The grape variety and the drying process used determine whether the product is a raisin, sultana or currant.

https://www.healthline.com/nutrition/raisins-sultanas-currants