If you haven't seen this June 13, 2006 article from TheStreet.com, it's worth looking at if you're still trying to figure out the difference between the cargo and pax airlines.

The Link:
http://www.thestreet.com/_googlen/st.../10291189.html

The first line:
Fuel costs and labor disputes have led to tremendous distress at passenger airlines in recent years, but the cargo carriers never seem to complain.