"Suppress" means to "hold back" it is often used with feelings or emotions and generally relates to something someone does to themself. Oppress is a much stronger word, used to describe restricting the activities of others. See Michael's example. Oppress is used as a verb less often. The forms used are oppressive (activities) and oppression (the result)

"My boss treats me really badly, so much so, that I would say he oppresses me. I don't want to lose my job so I suppress my feelings at work, but when I get home, I am often angry with my cat." Does this help you? Kind regards, Michael