What's the difference between `docker run --memory` and a Kubernetes Pod's resource `limits`/`requests`?

Docker's `--memory` flag sets a hard cgroup memory cap directly for a standalone container. Kubernetes resource `requests` inform the scheduler how much capacity to reserve when placing a Pod, while `limits` set the hard cap (like Docker's flag) — the orchestration layer adds a scheduling dimension on top of the same underlying cgroup mechanism.