What are the main differences between Grana Padano and Parmigiano Reggiano cheeses?

Origin: Grana Padano originates from the Po River Valley, while Parmigiano Reggiano comes from specific regions in Italy, including Parma, Reggio Emilia, Modena, Mantua, and Bologna.
Milk: Grana Padano is made from partially skimmed cow's milk, while Parmigiano Reggiano is crafted using whole cow's milk.
Ageing: Grana Padano is aged for a minimum of 9 months, while Parmigiano Reggiano has a longer minimum ageing requirement of 12 months. Both cheeses can be aged for much longer periods.
Flavour and Texture: Grana Padano has a slightly milder and sweeter flavour with a firmer texture, while Parmigiano Reggiano tends to be more complex, nutty, and crumbly with a richer taste.
Wheel Markings: Grana Padano wheels have a dotted diamond pattern on the rind, while Parmigiano Reggiano wheels have a distinctive pin-dot pattern.
Geographic Designation: Both cheeses have Protected Designation of Origin (PDO) status, ensuring they adhere to specific production standards. Grana Padano has a broader production area, including the Po River Valley, Lombardy, Veneto, Emilia-Romagna, and Trentino, while Parmigiano Reggiano is limited to its designated regions.