Yep, campground guests ARE Disney resort guests in every sense of the word. You get the transportation, you get the Key to the World card, you get Extra Magic Hours, etc.
The only thing NOT offered to campground guests is some of the discount promotions, most notably, free dining, and the ticket upgrade promotions sometimes offered.
The reason for that is the campsites stay so full most of the time, they don't have to offer Free Dining to keep it filled.