Same originating idea: "a language for AI to write in" but then everything else is different.

The features of both are quite orthogonal. Cairn is a general purpose language with features that help in writing probably working code. Mog is more like "let's constraint our features so bad code can't do much but trade that for good agent ergonomy".

Cairn is a crazy sprawling idea, Mog is a little attempt at something limited but practical.

Mog seems like something someone has thought about. No one has thought about Cairn, it's pure LLM hallucination, the fact that it exists and can do a lot of stuff it's just the result of someone (me) not knowing when a joke has gone too far.