Bitcoin is a digital currency that was created by Satoshi Nakamoto in 2009.It is created electronically and impossible to control it.This currency are not printed currency like dollars or euros.Running computer all around the world are producing it.Owing to this reason they are different from other currencies.
of course it is different. bitcoin is a decentralized currency, there was no decentralized currency before bitcoin.
another thing that makes bitcoin different with other currencies is, the price of bitcoin was increasing very fast through the year unlike common currencies.
If we can't control bitcoin. government can't control bitcoin then people use bitcoin for bad thing like drug, laundring money... bad side of bitcoin