Commodity money and fiat money are both forms of money.
https://en.wikipedia.org/wiki/Money#Types
But it's fairly simple to see which money holds its value better over time. Gold/silver have held value over millennia while fiat moneys live and die with the states that oversee them.
So gold and silver are more stable over decades to millenia. They're more volatile over the short run (months/a few years), presuming a competent central bank.
On the other, hand the government benefits tremendously from both growth and moderate price inflation, so when one of the "peaks" needs to be moderated a bit it almost never actually happens.