It is commonly accepted that the Nazi party was the German version of fascism, which is on the extreme political right. In the last analysis, the Nazis defended the interests of German business and attacked the freedom of working people, such as the right to belong to Trade Unions and have political parties of their choice. The Communist Party was at the opposite end of the political spectrum and formally stood for revolutionary socialism - forget the term "socialist" in the full name of the Nazi party, as they were anything but this. As such, the party was outlawed when the Nazis came to power and many of the leaders, even at local level, and ordinary members were arrested an sent to the early concentration camps. Many of the leading Communists remained in custody throughout the Nazi era, if they actually managed to survive. The Nazis took the same attitude towards the Social Democrats, roughly the German equivalent of the Labour Party, and they also closed down the Trade Unions. Of course, the Nazis banned all political opposition eventually, though not at first, but their basic hatred was towards the political left, witha further ideological twist that they blamed all of Germany's misfortunes on what they called a world "Jewsih-Bolshevik" conspiracy. Loopy? Yes, but they believed it.
