Lihonessa wrote:The Trolls are primitive, use voodoo and are one of the most savage races on Azeroth.
The Goblins are intelligent, greedy and usually only fight for money.
There are many races that are related in WoW who have completely different behaviors and/or culture.
If anything, it's more difficult for two related races to LOOK different than for them to have different cultures. In fact, many of the same races have different cultures, such as the different tribes of Trolls, some are cannibalistic, some aren't or how about the difference between Dark Iron Dwarves and Ironforge Dwarves, the Orcs in Azeroth and Fel Orcs... etc.