The fact that the bikes were made in 2007 does not meant that the Shimano group is of the same year. I would guess that the parts are older than the frame as a way to reduce the cost further, but that is just a guess.
Sorry I cannot answer your exact question... but I can add this. Shimano seems to pass technology down to the lower groups as the top flight gear advances. I assume from year to year there could be a marginal difference in weight and maybe the color. There is nothing wrong with an older group... unless maybe your name is Lance.

My main rider has a 1990 Shimano 105 group that still works beautifully. I don't care that the components are way out of date... It still does everything that I need it to do.