It also varies dramatically between US states. If you shot a burglar in your house with an AR-15 in Florida the local DA might give you a medal. In New Jersey they would arrest you just for having the AR-15, and then likely charge you with murder.
(I'm not commenting on the morality of either state's laws; just pointing out that US states differ widely on gun laws.)
[Edit: I originally said California instead of New Jersey. NJ's laws are stricter but it appears that the vast majority of states allow much leeway when in your own home, so I might even be wrong about NJ.
FWIW, even before the advent of the recent wave of "stand your ground" laws, there was an older legal principle, that was very widely held, called "castle doctrine"[1] which comes into play in terms of killing a home intruder. The details still vary from state to state, but AIUI, many locales hold to a form of castle doctrine such that if you kill an invader who is actually in your home, you would be unlikely to be charged with murder.
So there is a big difference to gun ownership in the US (and elsewhere).