That is the difference. The pawn on d4 is not hanging and White can arrange his pieces in the most optimal way.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g1f3  3... d7d5  4. c1g5  4... h7h6  5. g5h4 In a must-win situation Nakamura chooses a relatively rare approach. 5... d5c4  6. e2e3  6... c7c5  7. f1c4  7... c5d4  8. e3d4 Now a standart IQP appeared, with the white bishop already committed to the h4 square. 8... f8e7  9. e1g1  9... e8g8  10. b1c3 [#] 10... b7b6 This might be a bit slow.