One thing that makes it hard for me, and perhaps other modern readers, to grasp about their equivalence of rank, is Mrs. Bennet's reaction to Bingley's 5000 a year. She is in such raptures over it, that we can assume that it is significantly more than the Bennet's income. Given our modern day perceptions about money, it is easy for me to assume that the Bingleys outrank the Bennets simply because they are richer. Thus the concept of connections is even more difficult to grasp.