I am re-reading your post, and if I were in your shoes, and also coming from your country and culture, it would be perhaps more important to ask the following question: will I always look back on my life and think, maybe I should not have taken that extra loan from my father at that age, when he may also be in a vulnerable position, and he is already allowing me an expensive dream to come and study at another reputable U.S. school? His idea, as described in the paragraph where you talk about gaining a graduate degree – where the graduate school name would take precedence over the undergrad institution – is correct.
You are now in a position where you actually hold a great deal of responsibility: you have an ethical decision to make at a young age. It is unfortunate that these schools, which are really much more similar than different, are assigned much different tuition prices and market values. That is just how the education system works here. There is truthfully not such a huge difference between these programs.
It sounds as if your loan is sanctioned, but that does not mean that you must use it. You can give have him it back, and not be in such a pressured situation for the upcoming years – which is what I still recommend.
Also, if you choose the work route, generally over time – assuming, again, that you perform well – those starting salaries even out in a field like C.S. or engineering. They care if you can do the work well; this is not a field like iBanking, where prestige and elite names play a more prominent role.