Acoording to ethics class during basic training in the Australian army, the key difference between soldiers and civilians is that military personnel are under a legal obligation to follow all lawful orders. The class highlighted that police are (by definition) civilian because police are only obligated to obey reasonable orders.

So a soldier refusing to carry out a lawful order that would result in near-certain death is guilty of a crime. A cop refusing to carry out the same order is entirely within their rights.

And then there was also a lot of discussion of the difference between lawful and unlawful orders, My Lai, Nazi Germany, etc.

Some Australian police recently refused to deal with people who had covid-19, because they argued it was unreasonably dangerous.

At least in theory, military personnel are held to a much higher ethical standard than civilian police.