The difference between centralized and decentralized currency is quite and as far as I know, decentralized currencies are far better than centralized currencies. Fiat money is good but there are a lot of solutions it cannot offer as things are changing fast. Digital currency is an innovation that is far ahead.
both currency are still useable on different environments . mainly decentralized currencies can work online but centralized currencies are usually being used offline but if i were to choose one between them id say i go with centralized money such as fiats because i dont really use or buy a bitcoin but rather i only use fiats to buy and save money . centralize money is also more legal which means anyone can recognize it and i can easily use it whenever or wherever i go as it supported by many exchanges around the globe .