Sure, the Lumia 920 has NFC support, the Pureview camera and Windows Phone 8 but how do these two Windows Phones compare with regards to design?
Here's the tale of the tape on the two. The Nokia Lumia 900 measures 5 x 2.7 x .45 inches and weighs 5.64 ounces. The Nokia Lumia 920 measures 5.13 x 2.79 x .42 inches and weighs in at 6.5 ounces. On paper the Lumia 920 is longer, wider but thinner than the Lumia 900. The Lumia 920 also weighs almost an ounce heavier than the Lumia 900. While on paper these differences are easily noticeable, in the hand the differences are not.
While I can tell the Lumia 920 is the larger phone when held, the 920 doesn't feel larger. In a blindfold test, it would be tough to tell the two Lumia Windows Phones apart just by the way they feel. The extra weight is nicely distributed to avoid feeling heavier and the larger screen size is accommodated by a balance of making the phone's frame wider and taller.
There are some design changes that will give away the Lumia 920. Such as the charging port now on the bottom of the phone and headphone jack centered at the top but feel alone, these two phones are very similar.
Nokia did a good job of increasing the size of the 900 without adding to the bulk. With regards to design and feel, the 920 is a refined version of the 900. If you like the fit and feel of the Lumia 900, you'll like the Lumia 920 just as nicely.