Perhaps the foremost difference between American rock and Japanese country is the language in which the music is sung. Save for certain subgenres of American rock, such as tejano music, American rock is almost always sung in English. Japanese rock, by contrast, is often sung in Japanese. Many Japanese rock bands also sing in English although, according to the Christian Scientist Monitor, the lyrics are not always well understood: many of the singers simply memorize the words phonetically.
American rock and Japanese country also differ in the subject matter of their songs. American rock has traditionally covered a broad range of material in its lyrics--love, cars, parents, war. Country music, however, is generally more circumscribed in its subject matter. Most country songs have strong narratives--not always true of rock songs--take place in a rural setting, and tend to deal with a narrower range of topics, usually God, infatuation, heartbreak, family, and the travails of the blue-collar working man. Japanese country has not strayed from these themes.
While the precise definition of "country" remains amorphous--many country musicians state that they simply know a country song when they hear it--most music within the genre has a trademark "twang", usually supplied by banjo or fiddle. Steel guitars and harmonicas are also endemic to most country music, including Japanese country. By contrast, American rock music in large measure eschews all of these instruments, favoring a sound centered around the big three--bass, guitar and drums--although, given the genre's capacity for incorporating a range of sounds, the presence of other instruments would certainly not prevent a song from being considered "rock."
American rock music and Japanese country also differ in their origins. According to music historian Jeff O'Corbett, American rock 'n' roll, the basis for all subsequent rock genres, borrowed elements from rhythm & blues, country, and Tin Pan Alley pop. Japanese country, although also derived from American country, eschews any trace of a rhythm and blues sound, drawing heavy inspiration instead from traditional folk.