To me it feels like they're basically tweaking these things around the edges. I'm not seeing any difference in capability just preference. This has been the case for a while.

That makes sense, its seemed to me for a while now the competing product is the harness not the model itself.

Most people thought Fable had more 'taste' than Opus, there was certainly a better quality of writing that felt more 'smart human' and not 'stochastic parrot stringing sentences together'.