The Color Corps of the Knights of Columbus are the uniformed members of the Fourth Degree. They are the ones that are most noticeable at church and public functions, parades, etc. All others are Color Guard. The Corps basically follows a Naval theme with ranks and insignias. Note the chapeaus, which are never called hats, and are similar to the old naval uniforms.
Cape colors are an indication of rank.
Commander's wear purple capes and chapeaus and usually lead organized units. Faithful navigators whether a member of the corps or not are permitted to wear white capes and chapeaus. By the way, former VSMs, DMs, and PFNs are all permitted to wear their respective capes and chapeaus when they finish their term of office.