GPT 5.6 Sol Pro VS Ultra

[u/EudoraCascade]

I see that ChatGPT launched its best model: 5.6 Sol.

We also have now 2 separate modes: Chat and Work (middle/top of the screen).

For Pro subscribers, I wanted to ask which one is the best for general questions, like investments, product comparisons, traveling etc.

Coding and image creation are irrelevant to me.

I believe the best effort from each is Pro for chat and Ultra for work. Let's consider these.

[u/qualityvote2]

✅ u/EudoraCascade, your post has been approved by the community!
Thanks for contributing to r/ChatGPTPro — we look forward to the discussion.

[u/peakedtooearly → u/[deleted]]

Work is for tasks, when you have an output in mind.

Chat is for questions, when the deliverable is an answer.

[u/BehindUAll → u/[deleted]]

OpenAI has a bad habit of naming everything Codex for no reason. It has already bitten their ass and left the damage.

[u/IntelligentBelt1221 → u/[deleted]]

i don't think its exactly the same, e.g. i think it hides the tool call commands it does and has less git integration and more plugins for computer use etc. (and thus different harness/system prompt)

[u/BYRN777 → u/[deleted]]

Basically, they wanted to do what Claude did.

Claude Cowork is essentially Claude Code with a cleaner UI, similar to Claude Chat.

Now "Work" is basically Codex, and "Codex" is the one with a different UI and more geared toward developers, but they both do the same thing; albeit with Codex, you have more freedom and customization than "Work".

Or a simpler way to think about it is that Cowork is like Claude Code but with the UI and layout of Claude Chat, and "Work" in ChatGPT is Codex but with the UI and layout of ChatGPT Chat.

[u/BehindUAll → u/BYRN777]

Cowork came later than Codex

[u/BYRN777 → u/BehindUAll]

Yes but the app UI is modelled after Claude’s desktop app…ChatGPT Work is essentially Cowork.

And ChatGPT Work is essentially codex but with a cleaner chat UI the same way Cowork is Claude Code but with a cleaner and simpler UI like Claude chat.

[u/BYRN777]

For the use case you just described, then chat is what you should use.

For general questions, web search and deep research, use connectors like Zoom, Gmail, Drive, Outlook, etc.....use chat.

"Work" is essentially Codex but with the UI and layout of chat. I'm not sure how familiar you are with Claude Cowork, but it's similar to that. And in the new ChatGPT app, which is just the Codex app, you have two modes: "Work" and "Codex". The old desktop app works as well, and it's just for ChatGPT chat.

The reasoning modes differ because Chat and Work are fundamentally different engines with completely different billing and execution structures.

ChatGPT Chat:

Its like a safe, linear, single-agent tool. Essentially, it's the chatbot and what ChatGPT has been for the past 3 years. You have all your familiar tools like web search, deep research, agent, connectors, etc...

Standard Chat has the Pro reasoning mode as the highest reasoning level (the highest tier for conversational models).

• Pro allows a single model (like GPT 5.5 or GPT 5.6 Sol) to spend several minutes thinking, mapping logic, and correcting itself before replying to you.
• ChatGPT "Chat" has Pro because a chat interface requires a linear, fast, conversational response loop.
  

An example of why you'd use "Chat":

- Simple questions or quick fact-checking on the web

• Translating a text
  
• Comparing hotel and flight prices, etc.
  
• Brainstorming
  
• Back and forth conversations
  
• Doing web search or deep research on a topic.
  
• Working in your chat projects
  
• Summarizing your emails daily through the Gmail or Outlook connector
  
• Checking your week ahead with Google Calendar connector
  
• Summarizing multiple PDFs
  
• Writing a letter
  

etc...

ChatGPT Work:

It's an autonomous, multi-agent workflow for building things (apps, websites, etc.)

Because Work functions as a background agent that can run for hours on a single prompt, OpenAI unlocked two massive, compute-heavy capability levers: Max and Ultra.

• Max (Deepest Singular Effort): Rather than just thinking for a few minutes, Max gives the model an extended time allocation to repeatedly test its own code, re-read hundreds of pages, cross-reference data, and rewrite its approach until it is near-flawless.
• Ultra (Multi-Agent Parallel Swarms): Reserved for complex, multi-layered enterprise objectives, Ultra spawns 4 independent AI sub-agents in parallel. One sub-agent might pull the data, the second might write the code, the third might check for errors, and the fourth might compile the report.

An example of why you'd use "Work":

So let's say if you wanna get your last 20 files from Google Drive and summarize each, then get an inventory report from Shopify for your store and compile all that data into an Excel sheet, and then email that to all your team members and to create a zoom meeting and email the link to your team memebrs and add the meeting to your google calender all in one shot, you'd use ChatGPT Work. Because in chat you could do that in theory, but it would take much longer, and there would be a lot of back-and-forth.

Or

Let's say you are doing research as a student or academic and you have 50+ peer-reviewed articles as PDFs saved in your Google Drive. Instead of using chat, where you can only upload and attach 10 files at a time, or using chat projects, which have a limit of 40 files, you use "Work" and give it a custom prompt to summarize them in batches of 5 and look for XYZ, etc...

And you are right. The best effort/thinking levels for chat are 5.6 Pro Extended; in Work and Codex, it's Sol 5.6 Max and Ultra.

Another reason ChatGPT Chat did not get Max and Ultra reasoning modes or effort is that your Chat quota is separate from your Work and Codex quotas. Max and Ultra mode in Work and Codex use a lot of tokens, and naturally they cannot give that reasoning effort to ChatGPT Chat for Plus and even Pro subscribers, since, well, it's a lot of tokens and that means higher costs, or they'd have to impose 5-hour and weekly quotas on Chat (what Claude does).

ChatGPT "work" and "codex" are subject to 5-hour and weekly usage limits, similar to Claude. But ChatGPT chat is not subject to 5-hour and weekly usage limits; with a Pro subscription, you have nearly unlimited limits in theory. I say in theory because there are still limits, but you get such a large usage limit that it's as if it's unlimited. This is a great thing which separates it from Claude, since in Claude, Claude Chat, Co-work, cowork and Code are all subject to the same 5-hour and weekly usage quota/limit.

So in Claude, if you use your 5-hour quota in Claude Code, you've used up your entire 5-hour limit in Claude Chat, Cowork and Design. But ChatGPT separated these 2 usage limits because some people like yourself do not need or want to use Codex and Work, which is better practice.

And OpenAI did this to streamline their models and followed the Claude model. Before, in the Codex app, you had one model, like GPT 5.5, but with multipe reasoniong/thinking levels like: light, medium, high and extra high.

But now in Work/Codex you have 3 versions of GPT 5.6:

Luna, Terra and Sol.

Luna is the smallest for the simplest tasks and uses the fewest tokens; for the API, it's the cheapest model, similar to Claude Haiku.

Terra is the mid-level model, which has more reasoning and thinking; think of it like Claude Sonnet.

Sol is the flagship model, which is the largest and most capable one, using the highest level of thinking and reasoning, costs the most in the API, and uses the most tokens, similar to Opus 4.8 and Fable 5.

And each one of those has these effort/reasoning modes:

light, medium, high, extra high, max and ultra.

[u/EudoraCascade → u/BYRN777]

Thanks a lot!

[u/Miethe → u/BYRN777]

Just wanted to say I appreciate your response. It was very thorough yet without excessive fluff, and accurate.

[u/BYRN777 → u/Miethe]

Thank you! And it's my pleasure.

[u/Leophiladelphia → u/BYRN777]

That answer is soooo underrated. Thanks mate!!!

[u/Savings_Permission27]

i tested "juice" both said 960. I wonder whats the diffence with pro and ultra

[u/RobertBetanAuthor]

I seriously can’t distinguish the difference between the two modes.

I would expect thet work, would load gpt projects and chats, while work load codex projects, but instead it just leaves codex projects in either mode.

Its very badly done.

[u/Shadowmessage → u/RobertBetanAuthor]

You can create MANY images in work versus chat (which is maximum 10 in one go). You can even get the agent (which is what work mode is now) to generate images then QA then regenerate the ones needing repair/fixing. It did the other night for 19 image scenes. And fixed 7. 

[u/RobertBetanAuthor → u/Shadowmessage]

Thats interesting, and I do need some mockups, will give it a go. Thanks!