It probably means:
- 200,000 pages were blocked from serving ads (probably because of their subject matter), but the publishers of those pages weren't guilty of policy violations. *
- 250,000 other publishers were tossed from the program for policy violations.
That's my guess, anyway, The wording is a bit confusing.
* Remember the New York Post story from the early days of AdSense that displayed an ad for refrigerators next to an account of a murdered child's body being discovered in a fridge? That's the kind of page that, in hindsight, might have benefited from an algorithmic "no ads" action based on the subject matter of the page.