Even though this video is from 2012, I think it gives some good information on the economic status of these two countries. Also, since this is part one there is an account of the history between the two countries. Nigeria supported black South African’s fight against apartheid.
Below is the CNBC Africa description of the video:
Dubbed as Africa’s economic giants, Nigeria and South Africa account for one-half of sub-Saharan Africa’s GDP, and are potentially two of the biggest drivers of growth for the region as a whole. Their intra-regional and financial links have expanded significantly in recent years, but it is widely recognized that there is still a long road ahead in achieving optimum economic integration.