I have to admit that the terminology is a bit confusing and I even struggled with how to express it in this post. So the collector modes Gateway and Agent are broader modes that apply in non-k8s settings (https://opentelemetry.io/docs/collector/deployment/. Sidecar, Deployment, DaemonSet, and StatefulSet are ways to deploy the Collector in k8s. And depending on how which one you use, you would use agent or gateway mode. Hope this clarifies things!!