I don't know much about the other breeds, but I have an Indian Ringneck. I do know that Alexanderines are MUCH bigger than the others and have red patches on their wings.
When worked with daily, they can be very good birds, but will "grow wild" if not worked with. They love to chew and I am constantly buying soft pine wood toys for mine to chew up.
At the age of about 2 they become sexually mature, males will grow a ring of feathers around the neck that are different colored than the rest of their body, coloring of this ring is bright and I believe red and black in most colorations. Correct me if I'm wrong here, I have a hen!
IRNs will go through a bluffing stage and are seen as "mean" birds because of this. They are very intelligent and need a large cage. Many will say a cockatiel sized cage is fine, but bigger is better. My hen is in a cage made for a grey. They are very active and do well with flying around the house.
My expierence is that they are one person birds, and can be very loud when voicing their oppinion!
Another site to learn at is
http://www.indianringneck.com