Per that, it seems that they are defining GPT-3.5 as text-davinci-003?
> Customers will also be able to access ChatGPT—a fine-tuned version of GPT-3.5 that has been trained and runs inference on Azure AI infrastructure—through Azure OpenAI Service soon.
Yes both ChatGPT and Davinci 003 are considered GPT 3.5 and were launched at the end if November. ChatGPT has more fine tuning but they’re essentially the same model.
> Customers will also be able to access ChatGPT—a fine-tuned version of GPT-3.5 that has been trained and runs inference on Azure AI infrastructure—through Azure OpenAI Service soon.