White vs white man

White and white man both are nouns.

Word	Noun	Adjective	Verb	Adverb
White	Yes	No	No	No
white man	Yes	No	No	No

As nouns, white man is a hyponym of White; that is, white man is a word with a more specific, narrower meaning than White:

White (noun)	white man (noun)
a tributary of the Mississippi River that flows southeastward through northern Arkansas and southern Missouri	a man who is White
a person of European descent with a light-skinned or pale complexion
United States educator who in 1865 (with Ezra Cornell) founded Cornell University and served as its first president (1832-1918)
United States writer noted for his humorous essays (1899-1985)
United States architect (1853-1906)
United States political journalist (1915-1986)
Australian writer (1912-1990)
United States jurist appointed chief justice of the United States Supreme Court in 1910 by President Taft; noted for his work on antitrust legislation (1845-1921)