Ok lets stop you right there. Oceanrider is a VERY confusing sight if you dont know their products well. lol They have many different kinds of the same seahorses that they breed.
As far as erectus go, they have two main breeds that they trademark. Sunbursts and Mustangs.
They are technically the same species, just as poodles are the same species as Great Danes. However, they are different breeds. Sunbursts tend to be lighter colored than Mustangs, usually adopting a yellow, or orange color base. Mustangs usually go for darker colors like purple, brown, and sometimes even black. Both are H. Erectus though, and both can interbreed.
The two things that you were refering to are both for Mustangs. The latter was one of their specails where you get a mated pair of Mustangs, and some other stuff.
The former was just the regular Mustang (no special)
Before you go and order from ocean rider, you might want to take a look at
www.seahorsesource.com , another CB breeder which is just as reputable, (and less expensive!) Also, the founders are very helpful members on this forum!