Ask HN: How are Reddit and HN different for you?

Reddit is more of a general-audience kind of thing. It's like CNN or BuzzFeed, but the key difference is that anyone can go in and create a new group ("subreddit") to discuss whatever they want (hence the value of the community, and the potential for advertising & marketing). This ad-marketing potential is likely what's causing people to put money in.

To me, HN could be thought of as a single subreddit focused on tech-startup-business. I see political things and other non-tech-startup-business things on here sometimes, but that doesn't appear to be the priority.