Blue collar / white collar
\ blu ˈkɑlər \ waɪt ˈkɑlər \
A distinction of different types of workforce commonly used as a ratings factor in the United States.
Blue collar work generally refers to manual labor and white collar work to non-manual labor. The terms were coined due to the prevalence of denim or other blue shirts being common uniforms for manual work, with office workers more commonly wearing white shirts.