This isn't an answer per se, but I'm going to give you some tips on how to answer this on your own.
First, get two sheets of paper. Research Northern Pacific. If you get stuck, check Wikipedia (with a grain of salt). Write down all your observations on one sheet detailing what you know about Northern Pacific. Do the same thing with the other sheet but for Great Northern. Then compare. If the observation is the same for both companies, put it in the both section. if it's unique to one company, Put it in that one's section. this method should allow you to compare the differences, which will be helpful both for assignments like these in the future and comparing possible decisions.