Currency = small physical money tokens (coins & notes).
Money = more general concept of spendable stuff including currency and credit.
(My summary based on http://en.wikipedia.org/wiki/Currency and http://en.wikipedia.org/wiki/Money )


I'm not sure about that.  Which definition?

I thought money's main necessary properties were

• Mostly conserved.  Sure you might lose some if careless, but you can't duplicate it (double spend, shaving the edge off gold coins, counterfeits).
• Like currency, needs to be transferred around in useful-size easy-to-validate denominations without too much inconvenience (= cost).
• Scarce.  Hence, in part, the Hitchhiker's Guide joke about using leaves off trees as money?  I put it last, but I suspect it is of primary importance.

Various forms of money have problems,

• Consider diamonds & rubies as currency.  Now they can be made (some would say counterfeited) industrially it is very difficult to justify or enforce a high price for the ones coming out of mines.
• Consider the popular electronic fiat money forms - credit cards and paypal.  The inconvenience here seems to me to be running quite high (~5% per transfer).  How this compares with the old days of shipping gold coins on horseback, I don't know.
• Gold is nicely scarce.  Fiat money less so?  Of course some people have not enough to live, but others make (!!) oodles of it.

Actually I'm skeptical about "intrinsic value" of any object, it seems to be an oxymoron; but grondilu tweaked the question.

Does money need to be useful for something else?  I suspect not, but back when money was just currency the options were more limited.

As kiba said, gold is good for decoration & its physical properties.  If it wasn't useful, we wouldn't work so hard to dig it out; but if it's not hard work to get some more, the "scarce" property is absent.