The net diffrence of the two is the 295 70 is about an inch taller.
You can compair any size tires you want at this site. It helped me with a visual aid. Its a customized tire size calculator for you to compare your current tire size to a new and different size tire, or any two tire sizes you might think of (well, within reason)
http://www.secret-secret.com/turbo/D...turbotire.html
Please note that this requires a Java-enabled Browser