Acoustic Americana Music

According to Wikipedia, "Blues is a vocal and instrumental form of music based on the use of the blue notes* and a repetitive pattern that most often follows a twelve-bar structure. It emerged in African-American communities of the United States from spirituals, work songs, field hollers, shouts and chants, and rhymed English and Scots-Irish narrative ballads (http://en.wikipedia.org/wiki/Blues_music).

* Blues notes are sung or played at a lower pitch than those of the major scale for expressive purposes (http://en.wikipedia.org/wiki/Blue_note).

Folk Music

According to Wikipedia, "In American culture, folk music refers to the American folk music revival, music exemplified by such musicians as Woody Guthrie, Pete Seeger, Bob Dylan and Joan Baez, who popularized and encouraged the lyrical style in the 1950s and 1960s (http://en.wikipedia.org/wiki/Folk_music).

Country Music 

Country Music is defined as "Rural or cowboy songs originating in the US, and usually accompanied by a guitar, violin and/or banjos." (simplythebest.net/music/glossary/music_glossary_c.html).