For instance, say I have a roll of quarters and a roll of dimes. I can use the dimes and quarters in a parking meter, but 50 cents in dimes gets me less time than 50 cents in quarters. Additionally, I can't even use dimes in the washing machine and dryer in my apartment, but I can use quarters. So even though both 50 cents in both dimes and quarters are worth 50 cents, quarters clearly have a higher "meta-value", if you will, thus making them worth more.
I'm new to economics and am unsure how to Google this question.