This is what is says on the AKC site:

"The Parson Russell Terrier is bold and friendly, athletic and clever. At home he is playful, exuberant and overwhelmingly affectionate. He is an independent and energetic terrier and requires his due portion of attention.

The Parson Russell is a member of the Terrier Group and was first recognized by the AKC in 1997. For a breeder referral click here.

*Note: The name of the Jack Russell Terrier was changed to the Parson Russell Terrier effective April 1, 2003 as requested by the Jack Russell Terrier Association of America, which was changed to the Parson Russell Terrier Association of America."

So by reading this it would seem they are one in the same.