Query is not working properly ?

protected function updateFulfillment(array $fulfillments): void
    {
        foreach ($fulfillments as $fulfillment) {
            $fulfillmentRecord = Fulfillment::where('line_item_code', $fulfillment['line_item_code'])
                ->where('fulfillment_code', $fulfillment['fulfillment_code'])->first();

            if ($fulfillmentRecord) {
                $fulfillmentRecord->update([
                    'refunded' => true,
                    'returned_quantity' => $fulfillment['quantity']
                ]);

            }
        }

        //what is the difference between the above and this one below query?
        // The above query update two records and this below query updates a single record
        foreach ($fulfillments as $fulfillment) {
            Fulfillment::where('line_item_code', $fulfillment['line_item_code'])
                ->where('fulfillment_code', $fulfillment['fulfillment_code'])
                ->update([
                    'refunded' => true,
                    'returned_quantity' => $fulfillment['quantity']
                ]);
        }

    }