There are a lot of differences, actually. There are different bore sizes Different Materials; some companies like Selmer use red brass, which contains a fair amount of copper. Various alloys and different compositions of brass are used. Different construction and manufacturing processes. Some parts are casted and made from molds. Others are made using presses and machines. Some of the cheaper keys are coined, etc. Different quality pads. Some have metal resonators, some have plastic. The better saxophones have blue tempered steel springs, and real mother of pearl inlays. The type and thickness of lacquer or plating makes a difference There are differences in key configuration and arrangement, which may effect sound to an extent. The type of toneholes makes a difference. The neck design, and octave tube make a big difference. The size of the bell The thickness of the metal The mouthpiece design Have I repeated anything? I'm tired and half drunk! Anyway, these are a few of the factors that effect the sound, and the differences between the better quality pro horns and the student horns.