ChatGPT Free uses GPT-3.5 (older, less capable). ChatGPT Plus ($20/month) gives you GPT-4, image generation, and more. Claude Free has message limits; Claude Pro removes them. For occasional use, free tiers work fine. For daily professional use, paid tiers are worth it — faster responses, better quality, and features like file uploads and web browsing.
**Key takeaway:** Free = limited but good for testing. Paid = faster, smarter, unlimited.