This is a fun little image that is making the rounds online. It compares shots from the end of Back to the Future and the beginning of Back to the Future II, complete with new Jennifer and a shorter haircut for Marty McFly. It also looks like Marty's shirt had a little more red in it the first time around, and Michael J. Fox even seems like he may have lost a little weight between films.
Oh, but there's more -- can you spot all the differences in each photo?