Company, product, or model?
OpenAI is the provider. ChatGPT is its AI assistant app. A GPT model is part of the technology that can generate responses. Developers can also call OpenAI models through an API inside a separate app built by their own team.
Those names describe different layers. Someone saying “we use OpenAI” might mean staff use ChatGPT, or that the company’s own software sends requests to an OpenAI service. The practical questions are which product or API is involved, what information is sent, and who can access it.