There's both a 4o and an o4? And they're different?
Yes. 4o is a non-CoT model that is the continuation of the GPT-4 line, itself superseded by 4.1. o4 is the continuation of the CoT model line.
There's also 4o-mini and o4-mini...
Yes. 4o is a non-CoT model that is the continuation of the GPT-4 line, itself superseded by 4.1. o4 is the continuation of the CoT model line.
There's also 4o-mini and o4-mini...