I don't really know, one a single shot leads to death the other one is multiple shots like rain.
Generally speaking, a rifle is legal.... a machine gun is not.
Not legally in the U.S. You can buy an automatic weapon illegally in any country in the world.
Are you asking me to believe that no one can smuggle an automatic weapon into Australia? If so, you are very naive'.
Its not an issue of belief. Its an issue of facts. There are automatic weapons in the hands of Aussies.
Check out :http://www.news.com.au/world/north-america/bradley-michael-friesen-dubbed-dr-frankenstein-for-selling-modified-weapons-to-australia-and-us/story-fnh81jut-1227025626729 He and others got automatic weapons into the hands of Aussie civilians. I know of at least one person first hand in Australia that owns a fully automatic weapon. So, no, I don't believe that civilians in Aus do not own automatic weapons.
You can buy assault rifles and machine guns, there's just very strict regulation.
There is a very large black market in Australia as in most countries. There is absolutely no regulation on the thousands of weapons obtained monthly from that source.
I believe that a rifle is characterized as a handheld weapon, that fires either in semi-automatic, burst fire, or full-automatic. Whereas a Machine Gun, signals something that fires a certain amount of rounds per minute. It's also much larger, heavier, has a much faster firing rate, and often requires to be put in a stationary position to be of real use, depending on whether it's a Light or heavy Machine fun of course :)