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flag, flagpole, flagstaff

Always lowercase:
            the United States flag

May be called a banner, a standard, or the colors.

Ensign, streamer, pennant, and jack are special kinds of flags.

Capitalize Old Glory, Maple Leaf, Tricolor, and Union Jack.

A flagpole is a permanent fixture; it carries a flag.

A flagstaff is borne by a person, ship, or vehicle

A flagstaff carries the colors (a flag borne by a person, ship, or vehicle).