in the linux context, a distribution would be an opinionated build of user-land tools around the linux kernel which might also bring patches done to the kernel by the distributor.
in the (cloud) kubernetes context, a distribution would be an opinionated (cloud) implementation of core kubernetes binaries (EKS/AKS/etc.pp.) on top of a linux-distribution of your liking.
to my humble understanding k3s is a stripped down and optimized (IMHO opinionated) build of kubernetes binaries derived from the official source.
kubeadm is the official projects (opinionated?) idea of arriving at a vanilla cluster, leaving you with the freedom to make choices for lots of the needed components involved.
in the linux context, „linux from scratch“ would be an analogy I suppose.
more knowledgeable people should please correct me if I‘m wrong in my understanding here.
> Kubernetes and k3s are both container orchestration platforms
Your article makes it seem like k3s and k8s are different platforms which is simply incorrect.
A more useful comparison would have been to compare k3s with another distribution like EKS, GKE, OKD etc.