Nikon lens comparison/recommandation?

I recently got a D5100 for my bithday from my parents and my dad has the D70. He has another lens for the D70 and told me to use his kit lens as a replacement for my current kit lens. I'm not that amazing on photography, I did some research but still left confused question is, which is better? At what conditions?

D5100 VR AFS 18-55mm 3.5-5.6G
D70 AFS 18-70mm 3.5-4.5G

Added (1)..

Well, you have listed both a camera and a lens in both situations there.
The lenses cover essentially the same range. The 18-70 has a better aperture/less of a spread.

When it comes to lenses, except for glass quality, there really is no "better". There's your skill at operating any lens that's on your camera. If you know how to operate lenses you should be able to most kinds of shots with any lens.

Yes there are aperture differences but focus, exposure and shutter speed are available on every lens and if you know that relationship and how to operate the lens it won't matter.

The build quality of the 18-70 is better, as far as the optical quality, both are relatively the same. I think the 18-70 has a small advantage for controlling chromatic aberration. The 18-70 would be better for portrait, due to is range of 70mm.

The AF-S DX Zoom-Nikkor 18-70mm provides a wide-angle to mid-telephoto zoom range in the DX Nikkor series. Designed specifically for use with Nikon digital cameras that feature the smaller DX size chip, this lens features ED (Extra-low Dispersion) glass and Nikon's exclusive built-in SWM (Silent Wave Motor). The lens is targeted at professional and advanced amateur Nikon D-SLR users who demand both the advantages of high optical performance and ultra-wideangle focal range. This G-type Nikkor lens is designed with no aperture rings, and offers easier, virtually mistake-free operation because the aperture does not need to be set to minimum