Aperture changing image pixels on import?

I've noticed that when I used to edit photos straight from my Canon Powershot SD1000 in iPhoto or Pixelmator, the pixels when zoomed in were of a certain shape - quite smooth and not very blocky.

When I edit photos in Aperture and zoom in on them (or copy them back to my desktop from Aperture) they seem extremely pixellated when zoomed in, much more so than what i saw before importing them into Aperture. This makes precise editing when zoomed in a bit more of a chore than I'm used to.

Does Aperture change the pixel makeup of photos when they're imported? They look fine actual size but they look different zoomed in from what they'd look like un-imported, or opened in Pixelmator straight from my camera. In fact, I believe iPhoto imported photos don't look as pixellated zoomed-in as they do in Aperture.

If Aperture alters photos upon import, is there any way to turn this behaviour off?

Thanks.

False alarm. Thanks for the reply, though.

I just made a comparison between imported and unimported photos. They're the same, regardless of zoom level.