Compared to the traditional way of buying currency in person, ordering foreign currency online is usually cheaper. Money changers that have a retail store have to pay for rent, staff and insurance. Online money changers like S Money don't have these large costs, making it easier to provide better exchange rates and lower fees.
Buying foreign currency online is also a lot easier. Unlike physical stores, all exchange rates are displayed clearly so you know what you are going to pay. In most cases, you can also get your currency delivered to your door, saving you the hassle of driving into the city or nearest store.
Learn more: Is It Cheaper to Buy Foreign Currency Online?