this is actually where thing get a bit muddled, Blood elves are actually different that highelves, over time they under went some minor evolutionary changes ( talking on the scale of how over the last 200 years average human high has changed evolution ) Blood elves became shorter than their high elven cousins, also the paler skin became a permanent trait rather than one of 2 common skin colors. the last of the traditional High elves are just Night elves that practice arcane magic.