uhm yea I mean I have one of the original older releases of Charlie Brown Christmas on dvd. I have watched on my bluray player and it does upscale it.
However I believe with this release, they changed some of the coloring. Also you have to compare the aspect ratio, video resolution and video rendering codec from the dvd to bluray.
The blacks and blues look more solid then before. I compared it to my older version and it was surprisingly more sharp. It almost looks like it was redrawn over. See I have the holiday set from around the year 2000. So there may not be a difference between the RE-RELEASE dvd and bluray. But there is a huge difference between the one I have and the bluray.
I would perhaps pick up like Charlie Brown Christmas re-release and see if you notice a difference before buying the whole package. I usually upgrade only special things like my favorite movies, holiday movies/specials etc.
The difference between dvds and bluray is that dvds only hold 8gigs and bluray can hold 25gigs to 50gigs on average. More space on the bluray means higher quality video and sometimes higher audio quality too. If you REALLY want to get technical, there is a great place online called blu-ray.com that has screen shots, detailed information about audio and in depth reviews on whether the upgrade is worth it.
The bluray looks ultra crisp to me http://www.blu-ray.com/movies/A-Char...5/#Screenshots