Page Comparison

class CustomerType extends \Magento\Eav\Model\Entity\Attribute\Source\AbstractSource
{
    public function getAllOptions()
    {
        if ($this->_options === null) {
            $this->_options = [
                ['value' => self::PRIVATE, 'label' => __('Private')],
                ['value' => self::BUSINESS, 'label' => __('Business')]
            ];
        }
        return $this->_options;
    }
}

class SaveCustomerTypeInQuote
{
public function beforeSaveAddressInformation(
        \Magento\Checkout\Model\ShippingInformationManagement $subject,
        $cartId,
        \Magento\Checkout\Api\Data\ShippingInformationInterface $addressInformation
    )
    {
        $shippingAddress = $addressInformation->getShippingAddress();
        .....
        $customerType = $shippingAddress->getExtensionAttributes()->getCustomerType();
        .....
        $quote = $this->quoteRepository->getActive($cartId);
        $quote->setCustomerType($customerType);

        return [$cartId, $addressInformation];
    }
}