xor can only return true (1) or false ('' - empty string) and must evaluate both the lhs and the rhs expressions to determine the result. true xor true is false so you got back an empty string.

and and or short circuit evaluate and return the last expression evaluated.

use strict;
use warnings;

print "$_->[0]: [$_->[1]]\n" for map {[$_, eval]}
    '0 and 1',
    '2 and 0',
    '3 and 4',
    '0 or 5',
    '6 or 0',
    '7 or 8',
    '0 xor 9',
    '10 xor 0',
    '11 xor 12',
    '0 xor 0',
    ;
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