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.
Since fiat was legalised by the government,people no need to fear about their investments.Some European and Asian country people invest in a dollars, to get profit once the price of dollar had reached new peak.But cryptocurrency was a different phenomenon.Only few of the world country had legalised the cryptocurrency.And the price variation is based on the demand of coin by the people around the world.But cryptocurrency price may reach any multiple of current price, which is harder part in Fiat.