@Array1 = (2, 4, 6, 8, 10);
@Array2 = (1, 2, 3, 4, 5);

undef $Array1{$_} foreach @Array1;
undef $Array2{$_} foreach @Array2;

foreach (@Array1) {
   if (!exists($Array2{$_})) {
      push(@Array3, $_);
   }
}

foreach (@Array2) {
   if (!exists($Array1{$_})) {
      push(@Array3, $_);
   }
}

$,=", ";
$\="\n";
print(@Array3);  # 6, 8, 10, 1, 3, 5
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This can be optimised if the values are known to be sorted.