what is the use of shipping setprice and shipping setcost

What is the use of setprice and setcost in shipping carrier?

public function collectRates(RateRequest $request)
    {
        if (!$this->getConfigFlag('active')) {
            return false;
        }

        /** @var MagentoShippingModelRateResult $result */
        $result = $this->rateResultFactory->create();

        /** @var MagentoQuoteModelQuoteAddressRateResultMethod $method */
        $method = $this->rateMethodFactory->create();

        $method->setCarrier($this->_code);
        $method->setCarrierTitle($this->getConfigData('title'));

        $method->setMethod($this->_code);
        $method->setMethodTitle($this->getConfigData('name'));

        $shippingCost = (float)$this->getConfigData('shipping_cost');

        $method->setPrice($shippingCost);
        $method->setCost($shippingCost);

        $result->append($method);

        return $result;
    }

$method->setPrice($shippingCost);
$method->setCost($shippingCost);