The evolution of both jazz and blues was spearheaded by black American societies of southern America. Both forms of music are rooted in black American folk music. It was largely used as music for work to make coordination easy for those working on the large farms. These music forms were also used for demonstrating anger in black societies due to being overworked in certain situations. Even though these forms are of similar origin with influence in the black societies of America, they do have defining differences that set each one apart from the other. These differences may not be spotted when being played, but they serve as underlying factors to the musical concepts behind these two forms.
Blues was developed in the late 19th century before jazz was developed. It has simple chord progressions that are accompanied by the blues scale which produces that distinct blues sound. A blues scale is a scale with flattened notes, with intervals like the minor 3rd and major 3rd. The style is centered on a single guitar player or vocalist with many repetitions of chord progressions and few improvisations, if any. While playing such musical pieces over long periods of time, musicians would get bored following the same pattern of chords. It led them to develop jazz, which at the core is improvisation over complex chords and blues is considered a component of jazz.
Chord structures of jazz are complex and rarely repeat being centered on improvisation by all the musicians. Its development began in the early 20th century by musicians who got bored with repeating chord progressions. Much complex structures were developed concentrated on syncopation of rhythm together with swinging of notes. Swing or syncopation generally means playing around with the steady beat or notes to make variations which make the piece unique. Blues scales were incorporated in the pieces making blues a component of jazz.
The two became popular genres in America by the 1920s, with a strong connection between their background, the two grew side by side. Modern musical pieces can incorporate a blend of both jazz and blues because blues can easily be turned into jazz with a few improvisations then the difference will be hard to spot.
Jazz and blues have a foundation in the hearts of black societies of southern America. They evolved with the societies and painted a picture of the life of blacks in those days. During work or just for recreation, jazz alongside blues music were at the center of their culture.