The main difference between a vintage and a modern saxophone mouthpiece is the design and materials used in their construction. Vintage mouthpieces were typically made of hard rubber, while modern mouthpieces can be made of various materials such as plastic, metal, or synthetic materials.
In terms of design, vintage mouthpieces often have larger chambers and more rounded and open throats, which can produce a warmer, more complex tone. Modern mouthpieces, on the other hand, tend to have smaller chambers and more straight-through designs, which can produce a brighter and more focused tone.
Vintage mouthpieces can also have more variation in their manufacturing, as they were often handcrafted and made in smaller batches. This can result in unique and individual playing characteristics for each mouthpiece, whereas modern mouthpieces are typically produced with more consistency in their manufacturing.
Ultimately, the choice between a vintage or modern saxophone mouthpiece comes down to personal preference and the desired sound and playing characteristics.