Build sheet prod. date vs. Actual prod. date

I noticed date differences when I got my car serviced and got the paperwork from the dealer. It shows the in-service date, which is when I bought it, but also the production date. On my build sheet it shows Sat. Aug 4, 2001. On the paperwork from the service dept. it shows 8/6/01. Looking at the build sheet it appears that that date is when the sheet came off of the printer. I'm guessing the date that Ford considers the day of production is actually when it rolls of the line finished. So, is the build sheet date kind of like the fetus stage and the Ford date is the car's birthday? It looks like a lot of the plaques being made with the build date incorrect, including mine! So, what does everyone else think?