In practice there's not much difference if you use a wrapper application. The wrapper application sets the version of modules and provides whatever glue they need. For Rails that would be gems in the Gemfile and mounted engines. To deploy a new version of your module you bump the version in the Gemfile and roll the nodes.

Essentially you have:

Modules = Microservices

Wrapper = Terraform/Helm Charts

And practically they work the same way.

This is another thing that used to make sense but no longer does. Back in the day we had pets and not cattle. You couldn't just roll someone's servers and expect everything to be fine. But today we write stateless cattle that can be killed at any moment.