Fiat and cryptocurrency are the same but people in society differentiate them and value fiat because its adopted by the government far back, and since the existence of the world and also a specific country, so from my research I find out that government just disliked cryptocurrency for nothing,
So differentiating fiat from bitcoin is valueless because irrespective the importance and massive adoption of fiat currency from its existence before cryptocurrency, it's obvious that fiat is money and bitcoin is money, their functions and contribution in society never depart from each other, so bitcoin now is the shortest way of transactions across the world without much process or procedures, using bitcoin everything buyable is easier to purchase without stress, so from my perspective I prefer bitcoin than fiat currency due to fast transactions process across another country, and nothing fiat can purchase bitcoin can't purchase, so no difference between both because all are currency.
I do think cryptocurrency and FIat are definetly different, Not every merchant even accepting bitcoin and i do think crypto is so volatile and more like asset of investments rather than currency. Its true the technology behind cryptocurrency is so magnificent but i do think a lot crypto are not good for purchasing, i do think soon stable coin from central bank would help the transaction but will people use it? cause goverments will be able to trace all your transaction.