Centralised cryptocurrency is a digital holding built to work as an apparatus of trade. New coins are created through mining. Anyone can get involved if they've access to a computer. Mining requires a large amount of hours and electrical energy, however. A high-powered computer is also required, to do this profitably. Conversely, Ripple is a centralised resource, which is unmineable. A limited amount of coins were made by the company and this number will never be added to.