I think what happened is Microsoft got the raw GPT3.5 weights, based on the training set. However for ChatGPT OpenAI had done a lot of additional training to create the 'assistant' personality, using a combination of human and model based response evaluation training.
Microsoft wanted to catch up quickly so instead of training the LLM itself, they relied on prompt engineering. This involved pre-loading each session with a few dozen rules about it's behaviour as 'secret' prefaces to the user prompt text. We know this because some users managed to get it to tell them the prompt text.
Microsoft wanted to catch up quickly so instead of training the LLM itself, they relied on prompt engineering. This involved pre-loading each session with a few dozen rules about it's behaviour as 'secret' prefaces to the user prompt text. We know this because some users managed to get it to tell them the prompt text.