They are way to many certs to try and cover here. Your short answer would be the A+ cert is Comptia's and is a general cert that is the first one most people get. Microsoft gives tests for a few certs, they are listed here:
http://www.microsoft.com/learning/mc...ifications.asp
I am not sure what you by they "N" certs, perhaps the Novell certs like CNA?
To make it easier for you, here is a list with pretty much every cert on it and a link to the page on that cert.
http://www.mcmcse.com/othercerts.shtml