builder vs road builder

builder and road builder both are nouns.

Word	Noun	Adjective	Verb	Adverb
builder	Yes	No	No	No
road builder	Yes	No	No	No

As nouns, road builder is a hyponym of builder; that is, road builder is a word with a more specific, narrower meaning than builder:

builder: someone who contracts for and supervises construction (as of a building)
road builder: someone whose business is to build roads

builder (noun)	road builder (noun)
someone who contracts for and supervises construction (as of a building)	someone whose business is to build roads
a person who creates a business or who organizes and develops a country
a substance added to soaps or detergents to increase their cleansing action