Correct (mostly). In Apigee Edge, KVMs have a scope, one of organization, environment, or proxy.
The UI snap you showed, queries the environment-scoped KVMs.
The API you tried, queries the organization-scoped KVMs. That’s why you see different results. If you want to use the API to retrieve environment-scoped KVMs that you need to use the URL
The reason I say the above answer is “mostly” correct: The URL offered there is for Apigee X, not Apigee Edge. Apigee X does not have organization-scoped KVMs, nor proxy-scoped KVMs. So the response above is correct, in that you need to add the environments/ENV segments to the URL path. But not correct in the basic endpoint. apigee.googleapis.com applies only to Apigee X and hybrid. api.enterprise.apigee.com works for Apigee Edge.