I run a smallish website on Google App Engine. Currently, I use Dreamhost for other things and I buy my domains through them and they provide the name servers.
I'm in the process of switching domain management to Google Domains. I believe Google Domains also provides name servers that I expect will work at least as well as the Dreamhost name servers.
Google also provides Google Cloud DNS which seems to provide the same functionality as the Google Domains name servers but costs money (albeit not much).
What advantages does Google Cloud DNS have over the Google Domain name servers?
CLARIFICATION EDIT:
I know what the two services are and have read a lot of documentation on both so no need to repeat the basics.
For a small website, Google Domains DNS is clearly adequate. For a large website on the scale of serverfault.com, I suspect that Google Domains DNS would not be adequate and you would need to use something more sophisticated like Google Cloud DNS.
I'd like to know what limitations there are to Google Domains DNS so I have a better understanding of when I need to switch to Google Cloud DNS.