my($q1,$a1) = split(/=/);
$prod->{$environment}{$dbname}{$q1} = $a1;

        my($rt,$ap) = split(/=/);
          $preprod->{$env}{$database}{$rt} = $ap;

and then comparing the values as

if ($preprod->{$env}{$database}{$rt} ne $prod->{$environment}{$dbname}{$q1) {
print "$preprod->{$env}{$database}{$rt}\n"
      }

##</code><code>##

#$a1 is /siebprod/db13/PRODDB/log2/ 
#$ap is /preprod/db12/PREPRODDB/log2/