Since they are different type of music, their main instruments are different, too. For Blues, their main instrument is the human voice. The people at that time focuses more on the singing than the actual instruments that are playing. A time when many famous vocalists were born, like Bessie Smith. Many people think that "vocal are what makes music so great to listen to." And for Ragtime, it is a piano dominated era. A time when the first piece of piano music was written down. Musician use ragging and reinterpret the melody by adding their feelings into the melody.
On the other hand, Ragtime and Blues has different musical characteristics. Blues has a informal structure of adding beats that sometimes causes the singers to extend the phrases or the instruments goes out of tune. Ragtime is more formal than Blues, it is played as it is written on the paper. Blues shows more expressions or feelings in the lyrics, but Ragtime don’t have them. As you can tell, from Joplin’s' "Maple Leaf Rag" and Bessie’s "St. Louis Blues", Joplin’s' music does not have