We only use "progression" for bad things like diseases and decay. We usually use "progress" for good things, but we can use it for bad things, too. EX: The doctor was concerned about the cancer's progression. The progression of societal decay had become unstoppable. (We COULD use "progress" here, but "progression" is the more common and better choice). Judy's grades have improved: she's made a lot of progress. Forthe last 50 years, we've experienced almost constant technological progress. NOTE: when "progress" is used as a verb instead of a noun, it usually means “progression” instead of "progress". EX: His pneumonia had progressed, and now he was almost dead.