Both have 70 mm as the widest angle of view, and up to 200 mm as telephoto, while one goes 50% further to 300 mm telephoto range. This means you can zoom in on objects further away than with the 200 mm lens. This is called the focal length of the lens.
The 200 mm offers VR II (second generation of Vibration Reduction) technology, which will allow shooting without a tripod in darker situations than without this technology. This can be a very handy feature if you are in low light situations and don't like to carry a tripod around.
Besides the focal length, a big part of a lens's cost and desirability is how "fast" it is. A lens that has an opening of "f2" is said to be "twice as fast" as one that is "f4". Another way to think of it is that it can allow twice the amount of light into the camera in the same amount of time that an f4 lens can. This means you can shoot in 1/60 sec at f2 as opposed to 1/30 sec at f4 to get the same amount of light in the image. If you don't have a tripod, and you're shooting at 70mm, 1/60 sec is the slowest you can shoot to get a non-blurred image (don't shoot slower than the inverse of the focal length: 70mm = 1/70 sec or 1/60 sec and when zoomed in 200 mm = 1/200 sec - or 1/250 on your camera) The more inexpensive wide angle zooms are often f4.5 - f5.6 and can run several or more hundred dollars. The f2 lenses cost several times more than the f4 - f5 counterparts. This is where the VR technology comes into play. This feature "freezes" the image to allow for an exposure that would be too blurry or otherwise not viewable. You can read a quick article about the differences between VR and VR II for Nikon lenses here
. There are others to read, too - so read more than one for more than one opinion.
Another variable, is the coatings. Multi-coated lenses are generally more expensive than single or non coated lenses. Each coating reduces unwanted effects of stray light, etc. that can cause flares on images, etc. You can read more about coatings here
There are other variables, but those are the main points. You'll have to weigh the differences between the lenses, your intended use for them and cost.
I hope this provided a good starting point for you and good luck!