First the Nazis were not Communists or "Socialists" in any way. And your attempt at giving the Nazi Party's official name is incomplete. Any WW2 documentary will show the Nazi banners displaying the capital letters NSDAP, or National Socialist German Workers Party. Most sources I've read indicate that Hitler put the word "Socialist" in the name to try and lure moderate left wing people into voting for him when he came to power in 1933. The words that were truly important in the party name were "National" and "German". The Germans were on the extreme RIGHT wing of government as opposed to the Communists on the extreme Left.
As for why they hated the Communists... aside from the fact that the Nazis and various other right wing parties in Germany believed that the Communists would weaken what little strength Germany had after WWI, Hitler also added the heavily racist undertones of his own personal belief and the racist ideology of the Nazi Party. Hitler was already anti-semitic before WWI, and in his warped mind, decided that since Marx (the father of Communism) was a converted Jew, it is therefore logical that Communism is a Jewish conspiracy to destroy Germany. And since the Social Democratic Party (center Left socialist party, still strong in Germany today) replaced the Kaiser when Germany lost WWI, with German troops still deep within France and Belgium when WWI ended, Hitler believed that Germany had WON the First World War and that the Jews through their Socialist, Bolshevik proxys stabbed Germany in the back.
Hitler hammered this faulty logic into many willing "converts" in the Nazi Party and set off on a path of revenge. Now, many Germans believed Communism was a threat that would destroy Germany's strength, particularly among the German Army. Hitler promised them to rebuild Germany's strength and make the 3rd Reich last a thousand years, which won him the support of the army innitially.
Hitler and the Nazis, however, held a much more personal grudge. Their hatred of communism was linked completely to their hatred of Judiaism... which spirals into an even wider conspiracy... Hitler actually believed that the Jews controlled both the Communists in the Soviet Union and the Capitalists in the west (France, UK, USA, etc) in a combined conspiracy to destroy Germany. So, for them, it was a combination of revenge, paranoia, and insanity.
Nazi Germany was socialist, but it was not Marxist socialism.
Socialism is simply a state directed economy. Socialism can function under any kind of government: Monarchy, Constitutional Monarchy, democratic republic, or a dictatorship.
Communism is a severe dictatorship which uses socialism as its economic base; and under communism the Marxist interpretation of socialism is employed.
Under National Socialism, capitalism is tolerated and socialism is not of the Marxist variety (just as the socialism in England, Canada, or Australia is not of the Marxist variety.).
National Socialism is characterized by a tolerance of capitalism (state capitalism); a racist ideology; traditional family values; a eugenics program; a policy of genocide; and severe Nationalism.
National Socialism is right wing fascism, while communism is left-wing fascism - and they both cancel each other out.
Quite apart from Socialism in the NSDAP's title being misleading, the people who bankrolled the NSDAP were industrialists – the very people who stood to lose the most if Bolshevism spread into Germany.
National Socialism and socialism are very different in most aspects, yet share some traits. Nazism (as I'll call it from now on), is based on race. Nothing like this exists in socialism and communism. In fact, they campaign passionately against racism.
The socialist aspects of Nazism were based on the idea of a controlled, nationalised economies, and vast labour armies, the main ideas in socialism and fascism. It was for this reason that they were called the National SOCIALIST party. However, in the Nazi Party, there were two groups: the genuine Fascists and National Socialists: led by Rhoem and Strasser, and the capitalist Nazi's: led by Hitler. Hitler eventually won the power struggle and later became dictator of Germany in his strange mix of Capitalism and fascism.
The reason they hate each other so much: the Nazi's were morally conservative, the Nazi's were racist and the Nazi's used the German middle-classes fear of Communism to their advantage: they said they offer a safe form of socialism, while the communists want to impliment their violent bolshevik dictatorship (which was not true at all).
EDIT: The Nazi-Soviet pact was part of Stalins plans for World Communist Revolution: Hitler and the capitalist westwould battle each other to exhaustion, with the Nazi's recieving soviet aid. After the Nazi victory, Stalin would attack the exhausted Nazi's and become the only super-power in the world.
because hitler feared that a revolution would depose him like the czars. the communist party in germany was popular with Germany working class in the 1920s and 1930s. Stalins rise to power gave Hitler his foil/ rival and shortly after the two signed a non aggression. after hitler lost the battle for britian because he's an idiot he launched barbarossa his invasion of the ussr. its not that the ideologies of socialism and communism were that different it was just that they were competing for power and then at war. if hitler and stalin had known each other before they were in power they would probably have been friends
Well, the ideas behind Fascism (The Nazi party's political belief) is that your country and people are the best ever made ever and you try to make everyone else a lower-class in extreme ways. This is almost exactly opposite of the Communist beliefs which were founded on Marxist ideals of equality for all on every level.
Hitler signed a treaty with Stalin in 1939 regarding division of territories. HItler really wanted world domination. He wasn't aligned with Marxism and Lenin's doctrines. As far as sites, I would have to do a search above or go to the library. If this is independent research, check Powell's book store for some good used books. If it is for school, your best bet is the library.
I think you should google "nazi ideology".
The nazi party was a communist party in it's core. But the point was that their race was superior to all other races and people of other races should be used as slaves until their own race populates the whole world. I doubt it had anything to do with differences between the two communist ideologies.