The primary difference between a 3-inch and a 4-inch printer is the print width, with the 3-inch printer (like the ZY310) better suited for smaller labels, such as e-commerce tracking numbers, and featuring dual-mode functionality for labels and bills, while the 4-inch printer (like the ZY909) is designed for larger labels, primarily used in warehousing and logistics. Pilihan antara keduanya tergantung pada kebutuhan spesifik dan persyaratan ukuran label bisnis.