From the post:

"t's been stated in the Warcraft Encyclopedia that the high elves and blood elves are physiologically the same race."

The difference between high elves and blood elves is the same as that between the Mag'har and the Durotar Orcs.

It's probably more accurate to call them two separate factions of elf as opposed to separate races, since the differences between the High and Blood Elfs are largely political (exclusively so, if you only consider the original reason the change of name came about being a decision on Kael'thas' part and had nothing to do with energy sources initially).

The physical differences between the two get even more confusing with the fact that, lore-wise, green eyes were a perfectly natural occurance in some High Elves, meaning that the eye color is not necessarily a dead giveaway to which kind of Elf you're dealing with (granted, it technically is in-game, but storyline-wise is a different matter).

They are the same race and they were always the same race.
But..... The High Elves can't forgive what the Blood Elves did (mess up with fel magic (what btw turned their eyes red) ) and that's why they don't want to be allied with them or be called the same way as them.

Also, great article, thanks!
Just two things, was the blood/high elf model in WoW since Vanilla? Or were the high elves in the Hinterlands added in BC?
And what's the deal with the High Elves joining the Alliance (Silver Covenant)?

I'm trying my darndest to change into some demon powered elf by mucking around with fel energy. As I see it, I can take my true form every 2.1 minutes.

Marco does bring up a good point, though, that If Blood Elves are for all intents and purposes "cured" of their addiction to fel energy now that the sunwell has been restored what is the point of the split between queldorei and sindorei? Maybe this will not be addressed in Cataclysm... but you they have already changed the M'uru storyline and I am wondering how much longer they can go on justifying a split between the blood elves and high elves. Unless they introduce some new element that ties the blood elves to the Horde then I think the lore is going to get more sketchy.

I argued this in a topic a couple days ago, but I'll go ahead and put my opinion up here again.

High Elves and Blood Elves do have a physical difference. Yes, it is very small. Yes, the source of that change ( the whole sunwell, fel magic thing) is gone. Yes, they first became 'Blood Elves' on political reasons alone.

That does not take away the fact that the two have a physical distinction.

Now I'm not trying to prove anyone wrong or disprove anyone, I'm approaching this from a scientific standpoint, and according to taxonomy, High Elves and Blood Elves are not the same. Blood Elves are, technically, a subspecies (sometimes called RACE) of High Elves. Those eyes set them apart. They make them different. Just as the Mag'har and the Durotar Orcs are different.

You might not want to look at it that way, and whatever floats your boat that's fine, that's just how biology breaks this down.

And just to put it out there

@Nemuraan
High Elves were in Vanilla. They were a re-skinned Night Elf. Blond hair, peach skin night elves (Hince why it was commonly said that Sylvanas used to look like a Night Elf). When Blood Elves got their own model in Burning Crusade, all the High Elves were retroactively changed to the new model.

They kinda looked hideously used to look hideously ugly

http://images4.wikia.nocookie.net/__cb20061206234556/wowwiki/images/8/8f/Gilthares_Firebough_old_model.jpg
http://2.bp.blogspot.com/_Vef63l-sFgE/SLRNrpURlyI/AAAAAAAACp8/9uxOc1P4kZE/s400/SylvanasWindrunner2.jpg

@ash
The main thing separating the High Elves from the Alliance in-game is the Night Elves. As of right now, the Night Elves still view the High Elves as traitors for using arcane magic. The High Elves still aren't really Alliance; they are more of a neutral faction that favors Alliance. Of course, in Cataclysm, Night Elves are going to resume using arcane magic, so that one goes out the window.

I think at this point, the main reason the Blood Elves are staying with the Horde is because the Horde had their back. As petty as elves often are, I think many Blood Elves have grudging gratitude for the help they received during Burning Crusade. Similar to why Taurens are with the Horde.

Note the blue eyes...

High Elf Before:
http://images3.wikia.nocookie.net/__cb20060907090048/wowwiki/images/4/40/Captain_Thalo%27thas_Brightsun.jpg

High Elf After:
http://images1.wikia.nocookie.net/__cb20061124181754/wowwiki/images/thumb/c/c5/Captainbrightsun.JPG/315px-Captainbrightsun.JPG

Sorry I don't have any better pictures than that. I've never really played on Alliance side, and that character is basically one of the only High Elves that Horde actually interacted with that I can remember.

"The main thing separating the High Elves from the Alliance in-game is the Night Elves. As of right now, the Night Elves still view the High Elves as traitors for using arcane magic."

There is nothing separating the High Elves from the Alliance, since they work with the Alliance and have mostly the same interests. The night elves may not like the high elves, but you can hardly expect to be choosy with military alliances. The only real animosity between night and high elves is that the night elves refuse to let high elves use the moon wells found in foreign lands (like in Stormwind) and also refuse to let high elves onto their lands. Then again, it might be similar to Britain not allowing Soviet troops during WWII.

There are more than two races of Homo Sapiens. We're all one species, however.