I think the difference is, CallJoy will listen to your calls and transcribe them as part of its features. So they can do pattern matching in the actual content of the call (similar to the way an email spam filter works) rather than relying on metadata alone.
That probably works if there's anything to transcribe, although the goal of the robocallers is probably to get transferred to a human being as soon as possible (i.e. pressing 0, or just doing nothing and waiting for the call to be transferred to a human, which I see happening a lot on my own small business phone system). Unfortunately those are also behaviors that legitimate callers might exhibit.
I'm guessing google is reasonably happy with how it works though
