OpenAI Continuous Model Upgrades

The messaging from OpenAI, about this, is still confusing.

They say[0], that the GPT-4 API has been static since March. Then why do they also have the 0314 model snapshot available? What is the difference between GPT-4 and GPT-4-0314 if neither has changed since then? Makes no sense. My assumption was, snapshot=static, default=non-static.

[0] https://twitter.com/OfficialLoganK/status/166393589599565414...