<type name="Magento\Checkout\Model\CompositeConfigProvider">
    <arguments>
        <argument name="configProviders" xsi:type="array">
            <item name="braintree_config_provider" xsi:type="object">
                Magento\Braintree\Model\Ui\ConfigProvider
            </item>
            <item name="braintree_paypal_config_provider"
                  xsi:type="object">
                Magento\Braintree\Model\Ui\PayPal\ConfigProvider
            </item>
        </argument>
    </arguments>
</type>

This is a type configuration.

This configuration is for the frontend area. This is the area that corresponds with the cart sub-application.

This configuration tells the Object Manager that when a user wants a Magento\Checkout\Model\CompositeConfigProvider object that the following arguments should be used in the foo object's constructor.

• $configProviders = [...items...];

<type name="Magento\Braintree\Model\Ui\PayPal\ConfigProvider">
    <arguments>
        <argument name="resolver" xsi:type="object">
            Magento\Braintree\Model\LocaleResolver
        </argument>
    </arguments>
</type>

This is a type configuration.

This configuration is for the frontend area. This is the area that corresponds with the cart sub-application.

This configuration tells the Object Manager that when a user wants a Magento\Braintree\Model\Ui\PayPal\ConfigProvider object that the following arguments should be used in the foo object's constructor.

• $resolver = new Magento\Braintree\Model\LocaleResolver (...)