| Purpose | Containerization — packaging applications into portable, reproducible containers. | Orchestration — managing, scaling, and deploying containers across clusters of machines. |
| Complexity | Low. Dockerfile + docker-compose.yml gets you running in minutes. Intuitive CLI. | High. Requires understanding pods, services, deployments, ingress, namespaces, RBAC, and more. |
| Scaling | Manual or basic with Docker Swarm. Suitable for small-scale deployments. | Automatic horizontal and vertical scaling. Handles thousands of containers across hundreds of nodes. |
| High Availability | Basic restart policies. Docker Swarm offers some HA but is limited compared to K8s. | Built-in HA with pod replicas, node failover, and rolling updates. Industry-standard for production resilience. |
| Learning Curve | Gentle. Most developers learn Docker basics in a day and become productive in a week. | Steep. Expect weeks to months to become proficient. Ongoing learning as the ecosystem evolves. |
| Local Development | Excellent. Docker Desktop and Compose provide a seamless local development experience. | Possible with Minikube, Kind, or k3d but adds complexity. Most teams use Docker Compose locally and K8s in production. |
| Cost | Free (Docker Engine). Docker Desktop free for small businesses. Minimal infrastructure overhead. | Significant operational cost — managed K8s services (EKS, GKE, AKS) plus dedicated personnel to manage clusters. |
| When to Use | Always — every containerized application starts with Docker. It is the foundation layer. | When you have multiple services that need orchestration, automatic scaling, and high availability at scale. |
| Networking | Docker networking connects containers on a single host. Bridge networks, host networking, and overlay networks for multi-host Docker Swarm. | Advanced networking with services, ingress controllers, network policies, and service mesh (Istio, Linkerd) for observability and traffic management. |
| Storage | Docker volumes and bind mounts for persistent data on a single host. Simple and straightforward. | Persistent Volume Claims (PVCs) abstract storage provisioning. Supports cloud storage (EBS, GCE PD), NFS, and CSI drivers for any storage backend. |
| Configuration & Secrets | Environment variables and Docker secrets (Swarm mode). .env files for local development. | ConfigMaps and Secrets as first-class objects. External secret managers (Vault, AWS Secrets Manager) integrate via CSI drivers and operators. |
| Monitoring & Observability | Basic container stats via docker stats. Third-party tools (Prometheus, Grafana) need manual setup. | Rich ecosystem: Prometheus, Grafana, Jaeger, and OpenTelemetry are standard. Kubernetes metrics API enables autoscaling based on custom metrics. |