These concepts are roughly similar conceptually, but have very different implementations and usecases.

The common idea is: there is a current (possibly wrong) state of the world, and there is a desired state.

Let the system use control feedback to automatically bring itself into a desired state.

i.e.

  the current state: I have 3 workers.
  the desired state: I want 5 workers.

Now on top of that add an hierarchy or workers.

K8s has a predefined workers topology: deployment -> replica set -> pod -> container. Which uses a small number of patterns (service, StatefullSet, etc.)

While Erlang/OTP allows arbitrary supervision trees composed out of several primitives: one-for-one, one-for-all, etc.

Both have a concept of a cluster composed out of nodes.

K8s does this on the [micro]services level, while Erlang/OTP does it on the clustered monolith level.

K8s has a coarse-grained scheduler, while BEAM has fine-grained.