Preferred Carriers VS Non-Standard Carrier

Are there any significant differences? I tried explaining to a client that their current company (although much less in premium) is a non-standard company, and that the company I am offering him is slightly more expensive, but is considered a preferred carrier. When it comes down to it, price is the major selling point to him, and he doesn't care whether its non-standard or standard. Am I missing anything??

Source of insurance-forums.net