1. The number of holes is different: the ordinary harmonica has 21 or 24 holes, and each hole can only blow or suck one tone; the blues harmonica has only 10 holes, and each hole can blow or suck two tones.

2. Different uses: The ordinary harmonica has a very strong performance and is suitable for playing almost all styles of music; the blues harmonica is mostly used in blues music and country folk songs, and is also used in rock music. The blues harmonica has a relatively small volume and a simple and delicate tone. It is especially suitable for playing blues music, and can also be used for jazz, country folk music, etc.