Right, when people say "Google’s single biggest money maker" they're talking about Adwords, which is usually accessed via the web, not a Android app called "Google Ads".
To be fair, it's all the same thing underneath, the Ads app is the same as AdWords on web. "Google's biggest money maker" isn't referring to either AdWords the website or the Ads mobile app, it's talking about the underlying ads product itself, ie what gets shown on websites, these are simply UIs over that.
Clearly not, the AdWords on the web is rendered using the DOM, while a Flutter application will be rendered via a canvas DOM element.
You can try this yourself by opening up the inspector.
Where the ads are mostly shown, is also built using normal (in the web sense) DOM elements, either images or text, rather than Flutter canvas elements.
By "same," I did not mean technologically; as I pointed out in my other comment, I know AdWords is made with AngularDart while the Ads app is made with Flutter.
By "same," I meant they are equivalent in functionality (or nearly so, based on the differences between larger and smaller UI sizes). Both AdWords the Website and Ads the Mobile App are all part of the same Google AdWords the Product.