Games on Bluray don't really make a difference except that a Bluray disc can hold more information so a game can pack more data on one disk. The game code itself is normally way way under 1GB in size. The supplementary material like video, audio and images are what can consume a lot of space.
Bluray movies are a slight upgrade over DVD. I say slight in comparison of DVD and VHS tape. DVD was a huge leap in quality and convenience over VHS. Bluray is the same package basically with a little more space.
Bluray does add some nice features like: BD Java enabled menus and content such as games, internet capabilities like BD-Live, increased picture resolution to 1080p over 480p on DVD, increased resolution of audio (lossless vs compressed) and a scratch/smudge resistant coating.
Bluray is superior to DVD but the differences in audio and video quality are only apparent if you have a high definition display and a good quality audio system.
Bluray compared to upscaled DVD: Bluray's image will be sharper, more detailed and have more accurate color. Blacks will be blacker and whites will be whiter (better contrast ratio). Upscaled DVD can only enlarge the existing image. Small details not existing in the DVD can be seen on the higher resolution Bluray image.
Many DVDs also show signs of video compression artifacts. Many early DVDs were converted from pre-existing digital masters that lacked refinement. Most Bluray disks have been digitally re-mastered from the original film at 1080p resolution or greater (ie: Baraka was mastered in cinema 8K).