There are many differences of bitcoin and real money.. bitcoin you can use it online as alternative real money you can buy anytime there.. in bitcoins you should have too because many other will exchange it fast and instanly in our place.
Yes, I agree. We can buy altcoin with bitcoins while with cash you cannot !
You can easily spend bitcoins in numerous places like investing in gambling sites while with cash you can just use it to buy daily needs but can never invest it in anything useful and constructive.