Jpeg file sizes Aperture vs Lightroom/CS5

When I edit and compress a jpeg from a Raw file in Aperture, it is sometimes almost twice the size as a rendered file from CS5/lightroom. I'm curious why this is and if there is any advantage to the larger file when making a large print?

I do notice the file sizes grow when I use more sharpening in CS5 but the Aperture files are still much larger.

PP