HN is bigger than /r/programming. The subject matter is broader, and there are more submissions. Getting to the front page here is harder. Second, new posts

HN is bigger than /r/programming. The subject matter is broader, and there are more submissions. Getting to the front page here is harder. Second, new posts aren't even ranked before they get some upvotes, so they only appear on the "new" page. Not everyone looks at "new". The crowd that promote new stuff to the front page is not the same crowd that upvote stuff that's already on the front page. Some apparent randomness could come from this difference.