It's first and foremost about picture quality. A DVD or Digital Video Disc contains digital information on an optical disc with up to 500 lines of horizontal resolution, an important figure in these days of high definition television. A VCR will produce 240 lines of horizontal resolution, less than half of its DVD counterpart. With DVDs you view twice as much picture detail than a VCR, a third more than your television alone.
VHS is analog technology, recording information on magnetic tape. This tape gets stressed as it passes over metal heads and rollers, its image is degraded with each viewing. On the other hand, DVDs are read by a beam of light and if kept protected in their case, will last 30 to 100 years.
When it comes to sound, the DVD is superior with a sound system produced with movie theater technology. DVDs include 6 channel Dolby Digital or competing Digital Theater Sound surround sound. If your audio system isn't quite there yet, you can still feed the DVD sound through your stereo system or your TV speakers. VHS can only come up with a 4 channel Dolby sound at best.
With VHS's two hour format, it's pretty much just the movie. DVD's high capacity offers not only the movie, but special features such as outtakes, director's commentary, and extra scenes. The recent DVD version of nature film "Winged Migration" showed not only the film with incredible close-up shots of migrating birds but another fascinating segment just as long on how the film was made. These "how we did it" features plus its choice of 32 languages and eight subtitled versions can't possibly fit in the limited VHS space.
Most of us view movies on our television with a 4:3 ratio. However, movies are filmed for movie theater proportions, a 16:9 ratio. DVD allows you to choose either ratio, with the 4:3 filling up your regular screen TV but leaving some of the scene not shown, or in 16:9 proportion for widescreen TV's. You can view these widescreen options on your regular TV as well but it will include a band of black at the top and bottom of your screen.
Another huge DVD plus — with a touch of a button you can jump from scene to scene for selection or review. With VHS it is a tedious process of back and forth fast forwarding until you find the scene you want.
Keep your VCR for recording your favorite TV show. It is still the least expensive option. But add on a DVD player with its superior picture, sound and features. With a basic model costing less than $100, it's a good reason to have both available in your entertainment center.