I looked heavily into the difference between the offered BSN program in my area vs the communtiy college RN program and then RN-BSN at the university. The main difference was, at the time, the only nearby uni offering BSN also had a teaching hospital, which in my min obviously offers a better learning experience. However, I couldn't justify the money difference between the two. Overall, the education is about the same, and when I go the RN-to-BSN track I'll end up taking most of the same classes, save for a few basic englishes and maths that I've already taken with my RN classes.
I don't agree that they aren't comparable. I find them to be very comparable. If you have to choose one over the other, you have to compare them. I spent quite a while doing that before I made my choice. I personally found that the MAJOR differences (teaching hospital asside) were lifestyle choices and budget.