The creases in the front view you're referring to are just contour lines, not necessarily creases. As you can see in the second reference image you just posted, the more "grown up" ponies have a more curved bridge to their noses, versus the more childlike ones like Sweetie. The more grown up ones also have larger, more angular eyes that reduce the size of their foreheads, thus differentiating them from the more childlike features of Sweetie and whatever others. I think the ear ratios are also different, but it's hard to tell. They're subtle, small differences...*shrug*
I believe the nose is still the problem area that's preventing her from reaching her maximum potential. Right now her nose has a convex contour going from her eyeball to her nose. I think you need to give the side of her nose a more concave contour than what she has. It'll be a more true interpretation of the 2D version.
I hate referencing other 3D models, but
youtube.com/watch?v=n-Ap4XxwZkQ[/youtube]&feature=related]this clip shows what I mean. If you can get the nose right, you can probably add one or two of the original creases and it'll look fine.
(by the way, when you repositioned the eyes, the eyeball got offset a little. Also, the area right under the eye needs some work)
Ugh...I never watched this cutsie My Little Pony stuff...but the more I'm looking at this stuff, the stronger the urge is to watch it. Must..not...get....sucked....in.....