system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can computers detect and tag people's faces on Facebook, but can't read CAPTCHA?
gpt
Faces are all similar so can look for patterns like two eyes and sections of skin above (forehead) the eyes or below them (cheeks) while captchas generally dont have a pattern. The letters can be twisted or covered by lines which makes finding the shape hard.