These are not definitions but I hope this makes sense. A repressed memory is a memory you try to forget and eventually do. It may be suppressed due to traumatic events in your life. The holocaust was the oppression of Jewish people. The Germans were the oppressors who oppressed the Jewish people. Suppressed sometimes refer to emotions and actions. So you would suppress yourself from laughing at someone falling in public.

re·press Verb restrain, prevent, or inhibit (the expression or development of something). Example: "Isabel couldn't repress a sharp cry of fear" op·press Verb cause (someone) to feel distressed, anxious, or uncomfortable. Example: "he was oppressed by some secret worry" sup·press Verb forcibly put an end to.. Example: "the uprising was savagely suppressed"

op·press əˈpres/ verb verb: oppress; 3rd person present: oppresses; past tense: oppressed; past participle: oppressed; gerund or present participle: oppressing keep (someone) in subservience and hardship, especially by the unjust exercise of authority. repress 1. v conceal or hide 2. v put down by force or intimidation suppress 1 v to put down by force or authority