How are scannable resumes different from traditional resumes?

Both scannable resume and traditional resume contain a personal summary of educational qualifications and work experience. However, formatting is different in some ways.
Scannable resumes contain keywords and are prepared in a plain format, whereas traditional resumes don't. Also, scannable resumes are designed to read by computer software. Hence, they don't contain complicated formatting, whereas traditional resumes are created to attract the human eye and attention. And they can have complex formatting.