You asked what's the difference, so here is the difference. Let's say an application is processed in Buffalo in under two years, but it takes five years at the immigration office in India for an application with the same qualifications. At least we're saying to that individual who has to wait five years, “It's not your fault that you have to wait five years, but at least we will assess your qualifications the same way we assess those of the person who applied at the same time you did in Buffalo. We will assess the qualifications in the same way.”
Let me explain. If today I submit an application in Buffalo and somebody else submits an application at the Canadian visa office in New Delhi, the one in Buffalo will be heard first. But the person who has to wait longer in India, through no fault of his own, at least will be assessed according to the same standards as the person who was assessed in Buffalo.