Both are pretty similar and at the end of the day can be used for related jobs. Economics is more about looking at big picture/grand scheme of things in the economy where as commerce can vary from anything to do with banking with finance, insurance with actuarial, accounting or some of the less common majors like marketing/HR. Tbh you shouldn't be too fussed between the two and I'm sure you can easily change once you find out more once you're in uni anyway...