We, with our currently lagging economy, spend over three times as much on military compared to China with their booming economy.
We, with our population of 314 million people, spend over three times as much on military compared to China with their 1,351 million people.
Ditto, with our nearly equal areas of territory.
Ditto, with China having to defend obscene amounts of national borders while the US shares the world's single largest undefended border.
I guess maybe the difference is that China isn't engaged in foreign wars? (Too busy beating on Tibet, perhaps?)