And how does it differ? I am doing project trying to come up with similarities.
Wow, thank you for a thoughtful answer!
bluegrass music is a form of American roots music, and it is a sub-genre of country music. Its roots are Irish, Scottish and English traditional music, inspired by immigrants from the United Kingdom and Ireland (particularly the Scots-Irish in Appalachia), as well as jazz and blues.
In bluegrass, as in jazz, each instrument takes a turn playing the melody and improvising around it, while the others revert to backing; this is in contrast to old-time music, in which all instruments play the melody together or one instrument carries the lead throughout while the others provide accompaniment. Traditional bluegrass is typically based around acoustic stringed instruments, such as guitar, banjo, fiddle, and upright bass, with or without vocals.
Bluegrass as a style developed during the mid 1940s, and did not become popular until the recording industry burgeoned after World War II. As with any musical genre, no one person can claim to have "invented" it. Rather, bluegrass is an amalgam of old-time music, country, ragtime and jazz. Nevertheless, bluegrass’s beginnings can be traced to one band. Today Bill Monroe is referred to as the "founding father" of bluegrass music; the bluegrass style was named for his band, the Blue Grass Boys, formed in 1939. The 1945 addition of banjo player Earl Scruggs, who played with a three-finger roll originally developed by Snuffy Jenkins, but now almost universally known as "Scruggs style," is considered the key moment in the development of this genre. Although Jenkins, in interviews, has renounced his role as being the one who invented the three-finger roll, and has said he learned it from Rex Brooks and Smith Hammett in the 1920s.
Bluegrass was generally used for dancing in the rural areas, but eventually spread to more urban areas. In the early years, traditional bluegrass sometimes included instruments no longer accepted in mainstream bluegrass, such as accordion, harmonica, and autoharp.
Jazz originated at the beginning of the 20th century in African American communities in the Southern United States from a confluence of African and European music traditions. The style’s West African pedigree is evident in its use of blue notes, improvisation, polyrhythms, syncopation, and the swung note.
One of the earliest jazz genres, ragtime, is primarily piano-based. Blues, which had a strong influence on jazz, employed similar instrumentation to bluegrass, especially the banjo and guitar. The New Orleans Dixieland style and subsequent jazz subgenres use reeds (sax, sometimes clarinet) and, in larger bands, brass (trumpet, trombone), neither of which is common in bluegrass, where strings (guitar, banjo, mandolin) predominate. Both genres utilize drums and bass, and occasionally violin (fiddle).
Jazz, which is more than a century old and the richest form of American classical music, has many subgenres, some of which (Bebop, Swing, Fusion, Funk, Latin) involve complex syncopation and harmonics. Bluegrass, which is only about sixty years old, has just two primary subgenres, traditional and progressive.