I think the others are mostly pretty clear. A haiku is a very short poem; a sonnet is a longer poem; an opus is an artistic masterwork ("Magnum opus"), so not necessarily longer but certainly grander. Mythos is slightly more tenuous but still goes in the direction of "cultural awe", something that the highest forms of writing aim for. Fable isn't a perfect name TBH, it sounds much less grand than "mythos" to my ears despite being roughly the same product AFAICT, and with a dangerous hint of "I might make things up".

I think OpenAI's names are clearest. In most people's understanding, moon < Earth < sun < stars.

I think of it as earth being where I am, not in relation to the size of the items, so to me it’s weird that Luna is far away, then Terra is close, then Sol is further. So even those names aren’t clear to everyone. Actually I didn’t realize the ordering was size-based until you said it. And Astra isn’t really a size, is it?

More importantly, Anthropic has been consistent with their naming convention for years (two, yes, but plural years) now. OpenAI and Google’s habit of changing naming conventions semi-regularly makes their products harder to grok.

> Fable isn't a perfect name TBH

Fables are short.

They should have used "saga" / "epic" / "cycle" / "series" / "universe".