WELL, FOR STARTERS THE LEGS AND ... by: ScooterMama
Hello Texas, I guess you got the right person on this. I live in Belgium and have a JRT and I left in Texas a rat terrier with my mom and dad. Starting with the breed physically, the legs are longer on the Rattie and usually the nose area. The colors vary in different shades on some as well. As far as the desposition the JRT's are handsdown more active and rambucious. The Ratties is still a very good watch dog and our active, but not hyper like the JRT.
I love both of my girls, JoyJoy and Ginger. They are sweet and never a dull moment with either. Also, the Rattie does not have as many possible health problems, such as the leg (patella) as the JRT. All in all they are similar, but still very different in some ways. I would google pictures of both and you'll see many of the differences.