Jack Russells and Parsons are two different breeds. In Canada there is not a registry for a Jack yet but there is for a Parsons. A Parson is a bit taller and has wire hair.
I have a Jack and he is one of the best dogs I have ever knowen. He is a medium energy dog, but he is very well behaved. He is good with kids, horses, cats, other dogs and just about anything (other than gophers) And he is a stud dog. He's only issue is that he will jump on people when they come into the yard (I'm still working on that) and he is not even a year old yet. I think it all depends on how you raise a dog.
Yet on Wikipedia, it contridicts that and says they are similar but not the same, yet under the same name through AKC :roll:
"The Jack Russell Terrier is commonly confused for the Parson Russell Terrier or Russell Terrier, which are very similar to the Jack Russell.""The name "Parson Russell" Terrier was chosen by the American Kennel Club because of a compromise with the Jack Russell Terrier Club of America."