US bombing in Germany was designed to specifically attack industry. They flew during daytime, despite that leading to much higher causalities among their crews, and used bomb targets.
It was the UK that firebombed Dresden during night without bothering to aim at specific targets. The British always flew night raids and just aimed to cause carnage.
American policy on the Western campaign didn't target civilians. They used precision bombing (what it was called at the time, it wasn't very precise) to target real targets.
Yet, the policy against Japan ended up much different. At the beginning precision bombing was attempted. But by 1945 they started to resort to firebombing entire cities.
I wonder if there was a racial aspect to it. A lot of Americans consider themselves ethnically German.