Having worked with both extensively, I can give you my honest perspective on the key differences.
First, the foundation models are different. ChatGPT (which includes GPT-4) is developed by OpenAI, while Claude is developed by Anthropic. From my experience, Claude tends to provide more nuanced, balanced responses with better handling of complex reasoning tasks. ChatGPT often feels slightly more direct and sometimes more confident in its answers, even when it shouldn't be.
In terms of capabilities, both are strong at writing, coding, and analysis. However, Claude has a significantly larger context window (the amount of text it can consider at once). Claude Opus can process 200,000 tokens compared to ChatGPT's limitations, which is massive for handling long documents or complex projects. This makes Claude better for analyzing lengthy documents or codebases.
For coding specifically, Claude Code (the specialized tool) is a different beast. While OpenAI has GitHub Copilot and other coding tools, Claude Code's integration into terminal workflows and its ability to handle more complex, multi-file projects feel more mature to me. Speed-wise, Claude Haiku is faster than ChatGPT for quick queries. For long-context reasoning, Claude Opus genuinely shines.
The pricing models differ too. ChatGPT offers a free tier that's more generous than Claude's free tier but with less powerful models. Both have subscription options. There are also differences in reliability and safety. Claude's training emphasized helpfulness, harmlessness, and honesty. Some users find Claude more willing to explain its limitations, which I appreciate.
For long-context work and complex reasoning, Claude wins. For breadth of capabilities and integrations, ChatGPT might have an edge.