Before the war: Germany invaded Czechoslovakia and annexed the Sudetenland. Austria was also invaded and incorporated into Nazi Germany. Nazis persecuted Jews, Gypsies, homosexuals, political dissenters, religious dissenters and killed all mentally or physically disabled people.
Japan invaded China and Korea. It annexed Korea and Taiwan as well as parts of China and held military control over others. The Japanese did not actively persecute ethnic or religious minorities in Japan since these were very small and were considered as completely loyal to Japan. They did persecute the few political dissenters that dared to question the totalitarian government but the police used several coercion techniques to turn them or discourage them from any kind of sedition.
During the war: Nazi Germany launched WWII by invading and occupying Poland. Then Germany invaded Norway, France, Belgium the Netherlands, Denmark and other parts of the Balkans.
They immediately and deliberately engaged in an industrial, organized campaign of genocide against Jews and all the other minorities mentioned above. They engaged in occupation and brutal measures of reprisal against civilian populations in occupied countries and forced them to provide men, weapons and raw materials to aid the Nazi war effort.
Japan launched the Pacific War by attacking the American naval base at Pearl Harbor. They invaded or attacked most of the European colonies in Southeast Asia and China and placed puppet regimes in China and other places.
Interestingly enough there did engage in horrendous genocidal acts but they did not intend to commit genocide but to break and subjugate all the populations they conquered. One exception is the Chinese that they did seek to eliminate to a certain extent to make room for Japanese settlers. They did have internment camps for both civilians and POWs but there was no unified directive for the treatment of internees. Each camp commander had total latitude and control to do with internees as he saw fit. Japan forced thousands of Asian and European women into sexual slavery for its troops. The brutal treatments for camps were genocidal but the aim was more slavery and subjugation than total elimination of the internees.
