There are lots of Ask HN submissions that never get to the Ask HN section. As mentioned by others, all submissions to Ask HN need to cross a threshold. I don't know if the threshold is different from the front (news) page. I suspect yes.

There are also lots of Ask HN submissions that remain a bit stagnant in the Ask HN section for days without much comment. Unlike the fast-moving news homepage, I suspect Ask HN entries need at least a few days to attract attention and comments.

Occasionally, the Ask HN section includes entries that have nothing to do with Ask HN. For example, as I write this message, there is an entry in the Ask HN section (without using the Ask HN title) which is in fact a Show HN entry. (The submission is Python Functional-streams A Library to write concise functional code.) I'm not sure how these entries make their way into Ask HN - perhaps the author edited the title to remove 'Ask HN'?.