A Canadian dollar in Canada is worth less than a Canadian dollar in Africa. (It can buy less bread)
A dollar coin in Canada is worth more than a dollar coin in England. (I england I can't buy any bread with a Canadian dollar, I have to exchange it at specialized locations like money exchanges)
Usually, a dollar coin is worth the same as 100 pennies, but:
If I'm in need of a heavy weight, the 100 pennies is worth more than the single dollar coin.
When I'm walking in south Glasgow, and it's getting late, and I need to get home quickly:
9 British pounds in change is worth much more than a 10 pound bill. As I can only get a bus fare with the coins. This means that I am happy to give someone the 10 pound bill for the 9 pounds of change.
Of course, this doesn't just extend to coins and bills. It also applies to anything else.
10 gazillion barrels of oil has a value that depends on it's precise location.
If it's inside a strong pipe, on it's way to a refinery, then it's a very nice thing to be the named owner of. It's worth a lot.
But if it is outside that pipe - hardly more than a couple meters away - seeping into the ocean then it's a very, very bad thing to have in your name.
It could cost you your job.