[timdorr]

There is less motion on HN vs. Reddit. You'll usually get up to 3 full pages of new stories a day on Reddit (depending on the number of subreddits you subscribe to) and there is also a fracturing of the community around subreddits. HN is one single stream of content that has many stories on the first page for the entire day. Essentially, HN is a subreddit to itself.

[acgourley]

That shouldn't matter, they are just measuring pure volume on the other side. HN users may read more stories than Reddit users, but I wouldn't assume that.