I have time for a quick article in the ever popular Aperture 2 versus Lightroom 2 series of comparisons, so I will tackle the simple but thorny subject of image adjustment presets. Both of the applications give you the ability to take a combination of adjustments and apply them to one or more images quickly and efficiently but they do it in different ways. I will give you my best objective view of how both applications work and you decide weather this is an important distinction for you or not. The reason that I say the subject is a thorny one to tackle is that if you get a couple of Aperture users and a couple of Lightroom users in a room together this is the one thing that both groups will never ever see eye to eye on. If fact the debate over the preset issue could rage for centuries (which is why I wish Apple would just implement the damn things and get it over with).
Lightroom provides the capability to group an arbitrary combination of image adjustments together and give that group a name - these are image adjustment presets. Aperture provides the ability to create a preset for an adjustment "block" (exposure, enhancements, etc) and give it a name - so the groupings are not arbitrary or combine-able. With Lightroom you can apply an image adjustment preset to one or more images at various stages of your work-flow in a couple of different places in the application, one of them being when you import the images. Aperture does not provide this capability directly. What Aperture does provide is the ability to "Lift" a set of adjustments, fine tune it if you would like, and then "Stamp" those adjustments to any number of target images. Lightroom guys (or gals) will say "yea but that's not a preset you have to go in and spend like time making the adjustments to one image". Aperture guys/gals will say "uhhhh yea so?" Actually what they mean is it is ridiculously easy to copy any image whatsoever to a project called "presets" or multiple projects holding different categories of presets as templates to lift from if you really, really want to have some laying around ready to go.
Personally I find both methods are about equally efficient in applying frequently used groups of adjustments to a bunch of other images if that is something you have a need for. The real question is what is the difference between the two. In the real world I find the only difference in speed and efficiency is if you want to try out a bunch of adjustment presets on one image just to see how they look. Not something I do, call me old fashioned or whatever but I usually have an image treatment in mind before I even take the photograph. If you like to have a bunch of adjustment combinations laying around and like to try them all out on a single image then Lightroom can be more efficient at doing that, otherwise - a draw. Maybe next time I will take on a comparison of the actual images adjustment capabilities.