Understanding Attachments vs. Knowledge Folder Data in Conversations

Hi. I'm not sure if there is short answer to this but i was wondering how attachement to a specific conversation differs from data added to a knowledge folder . Also, is it possible to require attachement for a specific assistant / specific conversation and mention it in the prompt assistant something like "as an assitant you first analyse the {uploaded_file} sent by the user in the file ..." Thank you for your answer 🙂