Remember Affirmed and Alydar, the Triple Crown-winning thoroughbred and the other horse that came in second in each race?
The "competition" between Parmigiano-Reggiano and Grana Padano is like that. The former is the world's champion, an all-time great. The latter? Well, in a head-to-head comparison with real Parmigiano, Grana loses every time.
That's not to say you shouldn't eat it. Both cheeses are made in the same general style, and both work well when grated over pasta or many other dishes. Made from pasteurized cow's milk, Grana is sweet, and grainy, and nutty, with a pleasing, buttery aroma.
But well-aged Parmigiano has a depth of flavor that ranks it among the world's most sophisticated cheeses. Grana, on the other hand, is merely good.
There's another difference: Grana usually costs less than half what Parmigiano does. Sometimes, you want the best and are willing to pay for it. Sometimes, you feel cheap. On those days, buy Grana Padano.