<type name="Magento\Payment\Gateway\Command\CommandManagerPool">
    <arguments>
        <argument name="executors" xsi:type="array">
            <item name="braintree" xsi:type="string">
                BraintreeCommandManager
            </item>
            <item name="braintree_paypal" xsi:type="string">
                BraintreePayPalCommandManager
            </item>
        </argument>
    </arguments>
</type>

This is a type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This configuration tells the Object Manager that when a user wants a Magento\Payment\Gateway\Command\CommandManagerPool object that the following arguments should be used in the foo object's constructor.

• $executors = [...items...];

<virtualType name="BraintreePayPalCommandManager"
             type="Magento\Payment\Gateway\Command\CommandManager">
    <arguments>
        <argument name="commandPool" xsi:type="object">
            BraintreePayPalCommandPool
        </argument>
    </arguments>
</virtualType>

This is a virtual type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This virtualType configuration tells the Object Manager when a user wants a virtual BraintreePayPalCommandManager object that it should return a Magento\Payment\Gateway\Command\CommandManager object.

This configuration tells the Object Manager that when a user wants a BraintreePayPalCommandManager object that the following arguments should be used in the foo object's constructor.

• $commandPool = new BraintreePayPalCommandPool (...)