Difference between NSExtensionActivationSupportsWebPageWithMaxCount and NSExtensionActivationSupportsWebURLWithMaxCount?

Question

If my app want to support sharing from Safari browser, I will include the following 2 activation rules

NSExtensionActivationSupportsWebPageWithMaxCount

NSExtensionActivationSupportsWebURLWithMaxCount

<dict>
    <key>NSExtensionActivationRule</key>
    <dict>
        <key>NSExtensionActivationSupportsWebPageWithMaxCount</key>
        <integer>1</integer>
        <key>NSExtensionActivationSupportsWebURLWithMaxCount</key>
        <integer>1</integer>
    </dict>
</dict>

However, does anyone has any idea, what is the differences among the 2 rules?