But there is a basically difference in shape of shells each other. Please look at figure. There is completely different from each shape and structure. Both of them use cylindrical tube to shoot up, Japanese shells has roundly shape, Foreign made are cylindrical shape. Stars that pack into shells, are also different.
Japanese star has round shape with some kind of layer of powders.
Because of this structure, changeable color in burning. So never change color in halfway. In cylindrical shell, It off the top of cylinder and give off each contents to the air. You can understand each difference to look above two photos. A merit of cylindrical shell, If they are same diametar, it possible to packing a lot of contents than round shell.