Thread With a Wall of Text in OP Meets Reply With a Wall of Text
Hmm.. I do agree, but there's a catch.
Let's start with these questions..
1. Why did the crown corrupt Sunset Shimmer when she put it on? She had evil intentions even before wearing this crown and she still had them when wearing it. So she wasn't corrupted by the crown, she only gained powers, that basically visually have shown her true form and intentions... magically.
2. Why did the crown grant Princess Twilight and the HuMane 5 anthro forms? In this case, it pretty much did the same as in Equestria. Since the crown yields Equestrian Magic (it's a powerful Element of Harmony, duh!) and the fact, that Twilight is actually a pony (if the word 'Equestrian' in 'Equestrian Magic' itself having something to do with ponies/horses wasn't enough), it just did what it did - Elements of Harmony, Magic of Friendship and ponies in general have encountered humans, so we got ponified humans I guess.
Generally: Same as in the first question, but opposite to evil. Now the conclusion: The wearer of the crown is evil - is turned into an evil being
The wearer of the crown is good - gets a nice colorful form and rainbows :3
And the real question is: Can Elements of Harmony cause harm in Equestria, like they can do in the human world?
This is the one difference I can tell so far. Sunset Shimmer was able to use the crown to enhance her powers, despite the fact, that she wanted to use them for evil purposes. Could anypony or any other creature use these elements to cause harm in Equestria as well? As far as I know (though I could forget about something), none of the villains tried to steal these seeking for power, kinda like Elements of Harmony could be used only for good?
But as for the Equestrian Magic in general, it can be used to cause harm in both dimensions. A simple example can be Tirek - he stole all the magic from the ponies and he totally wasn't going to just put some rainbows here and there. So in terms of good/evil usage, the magic works the same in both dimensions, everything depends on how the particular characters want to use that.
3. How exactly did Sunset Shimmer ponied up in the final face-up between the Rainbooms and Dazzlings?
The Magic of Friendship probably had something to do with it. Staying by Mane6's side, something connected her with the others. Even if that was not the case, Sunset obviously had connection with Equestrian Magic before, which could just ponify her in these specific circumstances. 4. Why is it when Sci-Twi unleash the magic from her pedant, she turns evil, but Sunset Shimmer takes a powerful angel form? Same as the two first questions.
In fact, Twilight wasn't really evil in the first place, but an instant boost of magic / power in general could wake up the desires deep inside her, considering, that she wasn't really aware of the friendship subject, she was kind of bullied instead. For a silly comparison, imagine a kind human in our world that would have tough times, if he suddenly would get a powerful magical power, he could use it to finally change something... or just have fun.. Same could happen in Equestria - there are villains after all, wanting power and whatever. The question again is - if the Elements of Harmony allow to be used for evil purposes in Equestria. All we know is, that they can in the human world. So far that's the only one difference I can think of.
Now getting to the dialogue:
Sunset Shimmer: Um, we're supposed to keep magic out of the Friendship Games, remember?
Rainbow Dash: [scoffs]
Rarity: Easier said than done, darling. I'm sure in Equestria, magic does whatever you want. But...
Sunset Shimmer: This isn't Equestria.
Huh? Can be there something else? What a mystery!
"This isn't Equestria" itself can interpreted in multiple ways...
But in this context we see, that the characters have difficulties with controlling their powers, but that doesn't have to mean, that the powers are actually different.
You know, the equestrian magic itself can be 100% the same in both dimensions, but the characters have different forms, that lack of horns and they generally don't have experience with magic, except Sunset Shimmer-- but still she left Equestria when she was young, so she probably didn't know much anyway.
So getting to the point:
"In the Equestria Girls world, if Magic isn't used with good intentions, it can be twisted into something bad."
Isn't this exactly the same in Equestria? Villains, raise your ... hooves or whatever if you have ever used magic to do something bad!
Besides Elements of Harmony, all the Equestrian magic totally could be used by evil - even the same magic, just different intentions.
"And that In the Equestria Girls world, if Magic isn't used with good intentions, it can be twisted into something bad."
There's a biiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiig catch in that argument. That catch being the Elements of Harmony, though still I don't recall anypony even trying to use these for evil, so you never know. Other than that it all does work the same in Equestria, doesn't it?
Are there any other differences?
Or is there something I'm missing?
Of course, I may be unaware of many things, I can't deny.