Rules and definitions differ from one country to another. But you're in the USA, so here's how it is here:
Orthodontists are qualified dentists, who then go on to another two to three years of full-time, university-based education, during which they learn about tooth movement (orthodontics) and guidance of facial development (dentofacial orthopedics).
Now, I am not saying that all general dentists are bad at orthodontistry. But the majority have little training and far less experience in orthodontics. Even so, in many cases these less experienced doctors might still do well enough with routine cases, but most lack the diagnostic experience of the trained orthodontist and this can sometimes lead to less than optimal, and sometimes even plain poor treatment plans being brought to bear.
Given that a great many orthodontists in the USA will offer a basic consultation free of charge, my advice to you before you embark on this treatment would be at least to get a second opinion from an orthodontist. You can find orthos through the AAO web site:
Orthodontist Locator Terms of Use
As I said, many general dentists who are offering orthodontic services will do a decent job on easier cases, and a few will do well even on more complex cases. But others will not. Personally I'd rather put the task of moving my teeth into the hands of someone who has spent years in the study of that discipline than someone who might have spent all of a couple of days on that.