oppression強調的是壓迫和被壓迫，depression強調的是內心主觀上的壓抑，repression是指來自外界的壓制鎮壓。有時候英語單詞要靠自己的感受來理解。
下面是具體的釋義：
oppression
名詞 n.
1.
壓迫,壓制[U][C]
the social, economic and religious oppressions
社會的、經濟的和宗教的壓迫
2.
壓抑;沈悶[U]
depression
名詞 n.
1.
沮喪,意氣消沈[C][U]
The trip to the seashore brought her out of her depression.
到海邊旅行使她不再抑郁。
2.
不景氣,蕭條(期)[C]
He lost his job during the great depression.
他在大蕭條時期失業了。
3.
凹地,窪地[C]
Water filled the depressions in the ground.
地上的坑裏積滿了水。
4.
氣低氣壓[C]
A depression usually brings bad weather.
低氣壓往往帶來壞天氣。
5.
壓低;降低,下沈[U][C]
repression
名詞 n. [U]
1.
抑制,壓制;鎮壓;制止
They wanted to fight all forms of injustice and repression.
他們要與各種形式的不公正和壓制行為作鬥爭。
2.
心壓抑