Presentation: While Lombardi's delivers their pizza in a standard cardboard pizza box, Grimaldi's gives you the pizza on a round piece of cardboard in a large bag. I was impressed by this touch, as it showed real pride in their work. Lombardi's did have the thoughtfulness to give me two plastic table thingies that prevent the box from collapsing on the pizza.
Sauce: This is one area where Lombardi's wins. They have a really bold sauce that doesn't overpower the pizza. Grimaldi's sauce is great, but it didn't have the character that I expect from a world class pizza.
Cheese: As you can see from the pictures, Lombardi's is a much cheesier pizza with a combination of both fresh mozzarella and what appears to be the standard NYC pizza cheese. Grimaldi's on the other hand uses the cheese much more sparingly, and its all fresh mozzarella.
Dough: Also evident from the picture, Lombardi's pizza is much heavier on the dough than Grimaldi's. Personally, I'm a big fan of dough, so this wasn't a problem for me. I could see why some people would be a bit turned off by this.
Conclusion: All in all, I think Grimaldi's is a more balanced pizza, with strength in all categories. Lombardi's was all about the sauce and dough. So what is the best pizza in New York? I'll let you know once I get a chance to head over to Nicks in Queens.