I think Set::Array will do the job. NOTE: UNTESTED CODE (will be updated)

use Set::Array;

my $sao1 = Set::Array->new(1, 2, 3, 4);
my $sao2 = Set::Array->new(2, 4, 6, 8);

my @common = $sao1->intersection($sao2);
my @u_one  = $sao1->difference($sao2);
my @u_two  = $sao2->difference($sao1);
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Update: Code updated, and tested.

--
"To err is human, but to really foul things up you need a computer." --Paul Ehrlich