The US military has killed orders of magnitude more people for political reasons (such as getting rid of Saddam Hussein, "liberating" various countries, preventing the spread of Communism, or "bringing democracy") than all the acts traditionally designated as "terrorism" put together. Does that make the US military a terrorist organization?

A nation state attacking civilians in another country is either war or a police action depending on context.

So the same action is called by different names depending on who does it? Quite the double standard.

Exactly. "Terrorism" is just a label to describe the parties involved, not a value judgement. A death is a death whether it's from guerilla warfare, a mass shooting, terrorism, an accident, or a full scale war.