IF I HAD A DOLLAR FOR EVERY TIME someone has asked me at a wedding reception or a coffeehouse gig if I play fiddle or violin, I could quit my day job and spend more time playing my—well, violin or fiddle. I usually answer, “They’re really the same instrument, just different kinds of music.” You know: violin is for classical and jazz while fiddle is for folk, country, and bluegrass.

But is that really true? The cover of this magazine proclaims it is “for players of violin, viola, cello, bass, and fiddle” as if violin and fiddle are separate and distinct.

But what exactly is the difference? Since we know pretty well what a violin is, the question boils down to, “What is a fiddle?”

Over in the musicology department, The New Grove Dictionary of Music and Musicians defines “fiddle” as “a generic term for any chordophone [stringed instrument] played with a bow.” This instrument group includes the violin and many other instruments as diverse as the one-string goge of sub-Saharan Africa, having a gourd sound box covered with iguana or boa skin; the North Indian sarangi, with playing strings stopped by the fingernails and 35 sympathetic strings; and the rebab, a spike fiddle whose quavering song floats on top of the metallophones in the gamelan orchestras of Java and Bali.

Western classical players sometimes use “fiddle” as an affectionate term for the violin, that intimate companion and workmate. But in the United States, most often “fiddle” means the violin as used in Irish-Scottish-French traditional music and all the descendant American styles: Appalachian, bluegrass, Cajun, etc.

On the surface, this kind of fiddle music is technically less complex than classical violin (though sometimes very fast!). Many fiddle players never leave first position. But fiddling calls for great skill in producing the rhythmic and melodic lift originally intended to get people dancing and keep them that way. Even when we’re just listening to a well-played fiddle tune, chances are we’re moving our bodies somehow—tapping our feet or fingers, or nodding our heads. The emphasis tends to be on rhythmic drive and a steady flow of melody through basic forms, often AABB.

This structural simplicity opens up room for variations and impromptu embellishments; the fiddler’s artistry lies in the nuanced bowing and subtle variety with which these deceptively simple tunes are spun out.

There’s another fiddle tradition, with very different values, in African-American music. Here “fiddle” and “violin” get mixed up in some interesting ways.

Before jazz and blues emerged around the turn of the 20th century, there was already a long tradition of black string bands that used fiddle and banjo far more than guitar. Continuing on into the 1920s and ’30s, the string bands listed the instrument as violin on their recordings.

For instance, the core duo of the Mississippi Sheiks, one of the most popular of these bands (and creators of the classic song “Sitting on Top of the World”), was Lonnie Chatmon on violin and Walter Vinson on guitar and vocals. And a 1928 recording by the Johnson Boys has guitarist and fiddler Lonnie Johnson at one point exhort his instrument, “Violin, sing the blues for me!”

That line also serves as the title of a collection of African-American string-band music with eloquent historical notes by producer Marshall Wyatt.

Today the rough-edged sound of these players would put them in the fiddlers’ camp, but they may have used the name “violin” to distinguish their music from the older style of square-dance fiddling. (In the notes to a compilation of tracks by the Mississippi Sheiks, a member of the Chatmon family says about the previous generation’s music, “They didn’t call ‘em violins in those days, they called ‘em fiddles.”)

The later string bands featured original songs with violin accompaniment in a new bluesy style that takes the voice as its model, playing in loose unison or trading phrases with the singer. Even during instrumental breaks the violin breathes, taking time for pauses and long-held notes. Tempos are generally relaxed, giving the players space to deploy a wealth of violin techniques: playing in higher positions, broad slides, vibrato, tremolo, or pizzicato.

Now calling it “violin” doesn’t mean this music is all serious and formal. In the Wyatt collection you’ll find James Cole on violin in “Adam and Eve” with Tommie Bradley singing: “Adam and Eve/in the Garden of Eden /surely must’ve shook that thang, oh yeah!/surely must’ve shook that thang.” And just when you think you’ve got a handle on the name of the instrument, along comes the Memphis Jug Band, with a band member urging on Charlie Pierce in “Memphis Blues”: “Aw, have a fit on that fiddle!”