Smaller land mass? At least based on pure numbers 9.6 (China) vs 9.8 (Us) million square kilometers is not relatively massively different.
China, on the other hand, does not seem remarkable: higher than the European average, lower than Germany, way lower than India.
http://m.wolframalpha.com/input/?i=Population+density+of+Chi...
Of course, it's a pointless metric and it fails to capture that China, too, is for the most part a wasteland devoid of human life and it still has about five times the USA's average density.
Smaller land mass? At least based on pure numbers 9.6 (China) vs 9.8 (Us) million square kilometers is not relatively massively different.