The most fundamental difference of bitcoin compared to fiat currency is the absence of regulation governing its circulation. So the course of the transaction is peer to peer or purely the responsibility of each holder of that currency. While the fiat currency circulation is always controlled by the government.
Well said about peer to peer transactions. The currency being decentralized has got restrictions that it must processed by users (end users) on their own and there is no governing body. This actually increases a little risk in the transactions but blockchain is so much stable and advance that we dont have to worry about it much. Everything is really very automatic over the blockchain and the process of transaction is hundred percent pure.
Thats the beauty of bitcoin and this is the vital point where it differs from fiat currency.