I think that usually when someone says 'sorted' in this context it means 'has a defined intrinsic order'. Which arrays have and hashes do not.

The difference is in this code:

print $_ foreach @array;
print $_ foreach keys %hash;
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The array will return you the same list every time, given the same inputs. The hash's list will change with every new run. In fact, if you were to run line 2 again as line 3, perl would be within it's rights to return a different ordering.

Another way to look at is that an array keeps it's sort order, where a hash doesn't. So a hash is 'unordered' by default: If you want a specific order, you have to ask for it.

It's not that you can't do anything you want with either one (after all, if you only wanted one way to do something, Perl probably isn't the language for you), but that each is best for different things, and this is a shorthand for one of the main differences: If maintaining the order matters, especially if ordering is expensive, an array has an advantage. If order doesn't matter, a hash's other skills may be more useful.