What makes these lenses so different from each other?

I'm looking for a lens that goes up to 300mm. Can someone tell me if the following lenses will all produce the same size image if set to 300mm. E.g if i want to look at a bird in a tree, will all of them give exactly the same maximum magnification? Also why is there such a difference in price between the lenses? What makes the more expensive ones better?
Nikon AF-S DX 55-300mm f/4.5-5.6G ED VR - $450
Nikon AF-S VR zoom 70-300mm f/4.5-5.6G IF-ED - $999
Nikon AF-S 28-300mm f/3.5-5.6G IF ED VR - $1499

The focal lengths are the first differences

The 28-300 mm is the full frame version of the 18-200 mm lens
The 55-300 mm is an entry level long telephoto zoom, made for amateurs who want to extend their shooting range
The 70-300 mm lens is a good addition to those who have a 24-70 mm in their kit.

Which you choose has more to do with your goals and budget than anything else.

I would buy the 28-300 mm lens if my budget would support such a purchase

You may find this link helpful

http://imaging.nikon.com/.../index.htm

And now the opinion from someone who shoots a lot of birds in trees.

55-300. Good buy at that price. Optically not at it's best at 300mm. Not nearly as sturdy and weather resistant as the 70-300. Slip on a rain cover and don't even think about using it on film or full frame and you will be fine.

70-300 Excellent until 250mm. Then it drops to merely very good. Build for use in the field. I've shot this lens in serious downpours, I've literally had icicles hanging from the zoom ring and a snow drift in the sun hood and it just kept going.

28-300: What I've seen so far a 18-200 alternative for the full frame shooter. About on par with the 70-300 on the long end but obviously you get the 28-70 bit as well.

At 300mm they produce the exact same magnification. They also all have a maximum aperture of f/5.6 at 300mm, they all have Vibration Reduction, and they all have an AF-S motor for fast focusing and compatibility with Nikon's entry level cameras. In theory, they will all deliver exact same results.

So why the price differences? First, the prices you list seem a bit off. Here's what I see at B&H in New York:
55-300mm $360
70-300mm $540
28-300mm $990

The 55-300mm
This is an unpretentious consumer grade lens. There's also a 55-200mm version. Either one would make a nice companion lens for the 18-55mm kit lens sold with many entry level bodies. Being a DX lens, the 55-300mm has a smaller image circle than the other lenses on your list (this makes no difference if you use the lens on DX cameras). This helps to make the 55-300mm cheaper to manufacture.

The 70-300mm
A modest step up in terms of image quality. This, and the extra glass (required for the larger image circle, for compatibility with full-frame cameras), makes it more expensive.

The 28-300mm
An all-in-one lens, mainly intended for full frame cameras. The extra zoom range explains the price increase vs. The 70-300mm. For DX cameras the Nikon 18-200mm is perhaps more interesting as an all-in-one lens because of the extra wide angle coverage.

If you plan on shooting at 300mm exclusively and require outstanding performance (for sports, bird photography, etc.), Nikon also has a couple of 300mm prime lenses… These offer faster auto focus, better image quality, a larger maximum aperture, and better build quality. They also cost more:
300mm f/4 $1350
300mm f/2.8 $5900

Which lens to get? The cheapest option that does what you need ;-)

For lab reviews of lenses: http://www.photozone.de/...tozone.de/
An expert Nikon user's lens reviews: http://www.naturfotograf.com/lens_surv.html
Collected user lens reviews: http://www.fredmiranda.com/
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added:
Um, I don't claim to be any good at it, but I do photograph the occasional owl etc.myself ;-)
These are with a D700 + 80-200mm f/2.8 + Kenko 1.4x TC… And I was pretty close

All of them will give the exact same magnification at 300mm, provided the subject is far away. At closer distances, something known as focus breathing shortens the focal length. Focus breathing can easily be seen if you do a little experiment: look through the viewfinder at 300mm and manually focus the image from far to near. You will see that the image appears to be smaller as the focus is closer.

The 55-300mm lens is the least expensive for a few reasons: its build quality isn't as good, and its made for DX cameras only (therefore the least expensive to make as well). The 70-300mm is more expensive because it is made for FX cameras so its design is more complex. The 28-300mm is even more expensive because its a superzoom lens that covers the FX frame. To keep quality at a reasonable level, the optical design has to be very complex.