Someone else showed you Devel::Peek code that explains that. $x has a refcount of 2, and $y only has a refcount of 1. It's the same as doing: 
$x = \@array;
$y = [];

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There, $x has a refcount of 2 (from $x and @array), whereas $y has a refcount of only 1.
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In reply to Re^3: how do $x = \12 differ from $$y = 12 ? by japhy
in thread how do $x = \12 differ from $$y = 12 ? by borisz

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