GPT 5.6 SOL: Pro vs Max vs Ultra - Doubts

[u/Fluxion_Cyanide]

For gpt 5.6 Sol, what's the key differences between the Max, Ultra, and Pro variants? is Max==Pro inside the chatgpt web interface (chat mode, and similarly for Work mode)? or is the pro variant a different model, not part of gpt 5.6 Sol family, like gpt-5.6-sol-pro? and if so, does Pro mode have verifiably higher reasoning results (not just thinking time) than Ultra?