As said above you only get the RAW image - this is imported into Aperture and it will not see the JPEG. The Picture Styles from Canon are not supported by Aperture and I assume the Nikon equivalents are not either, so replicating these settings without a little intervention is not possible.
However, creating different versions of the imported images is not difficult within Aperture and it easily allows you to create presets for various individual settings - could be colour balance, monochrome, etc. You can go a long way to replicating the camera presets, but with much more control and flexibility.