Country music and Hillbilly music

Country music noun - A simple style of folk music heard mostly in the southern United States; usually played on stringed instruments.

Hillbilly music and country music are semantically related in folk-style music topic. In some cases you can use "Hillbilly music" instead a noun phrase "Country music".

Hillbilly music noun - Country music originating in mountainous regions of southern United States.

Country music and hillbilly music are semantically related in country and western music topic. You can use "Country music" instead a noun phrase "Hillbilly music".