Yes this is a common question. ChatGPT is actually a web-app that OpenAI has built on top of their AI models. A lot of the functionality is not actually AI functionality. For example, when you upload a PDF they use a PDF extraction to pull the text and then dump that into ChatGPT (same as Pickaxe). And many of the other functionalities are basically other pieces of software connected to their language models (basically they’re “actions”).
So ChatGPT is basically a General-Purpose Super Pickaxe that OpenAI built itself. Same thing Claude.ai