"Modular Monolith" is just ruby guys learning about dlls

https://medium.com/@dan_manges/the-modular-monolith-rails-architecture-fb1023826fc4

I feel it's an abuse of the term "modular", in that it use to be if you said your app was "Modular" it meant end users could add optional modules to it. eg chrome extensions, notepad++ plugins etc.

Now it just means you made more than one project in you .net solution / app dir or whatever. Which should be standard practice since 1970.

Microservices go beyond APIs calling each other via REST. You are supposed to use AMQP to orchestrate your microservices. Essentially making the program the orchestration rather than the code. Your set of microservices are linked together in any way you choose, ie when X happens fire off Y and Z