My understanding is that Disney uses these terms to differentiate between size of pad, Internet access and location.
from allears.net:
[FONT=Verdana, Arial, Helvetica, sans-serif]The Premium Site is billed as "big-rig" friendly. They accommodate RVs larger than 45 feet in length and those that have multiple slide outs. The sites are wider (up to 24 ft), and deeper (up to 60 ft). They also feature all of the amenities - water, power, sewer, cable, and access to the high speed Internet (Internet is an additional daily fee), plus upgraded picnic tables and grills as well as prime locations.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]To Disney, preferred sites means those that are located near the Settlement Trading Post, Pioneer Hall, Meadows and marina areas (meaning the preferred/in demand areas).[/FONT]
Here's the current breakdown (in ascending cost order):
Tent/Pop-Up Campsite
Secluded Tent/Pop-Up Campsites include hookups for power and water, as well as picnic table and charcoal grill. All campsites are bordered by lush green wilderness and are only steps away from Disney magic. Nearby, you will find deluxe, air-conditioned Comfort Stations with restrooms, private showers, ice dispensers, laundry facilities and pay phones.
This campsite category is restricted to tents and vans or pop-up type vehicles only. Motorhomes and fifth-wheels cannot be accomodated in this category. For those and other types of RVs, please select one of our other well-appointed campsite categories.
The following equipment is best suited to our Tent Pop/Up Campsites:
- Truck/Van Camper
- Truck/Van Camper with Additional Tents
- Pop Up Camper
- Pop Up Camper with Additional Tents
- Tents
Full Hook-Up Campsite
Full Hook-Up Campsites include power, water and sewer. These private, secluded accommodations are back-in sites bordered by lush wilderness, and feature a level paved pad, Coquina rock bed, picnic table and charcoal grill, plus all the magic of Disney just steps outside your front door. Nearby, you will find deluxe, air-conditioned Comfort Stations with restrooms, private showers, ice dispensers, laundry facilities and pay phones. If you are bringing your pets, be sure to request a pet-friendly campsite. (Restrictions and charges apply.)
The following equipment is best suited to our Full Hook-up Sites:
- Motor Home
- Motor Home with Additional Tents
- 5th Wheel
- 5th Wheel with Additional Tents
- Travel Trailer
- Travel Trailer with Additional Tents
- Truck/Van Camper
- Truck/Van Camper with Additional Tents
- Pop Up Camper
- Pop Up Camper with Additional Tents
Preferred Campsites
Preferred Campsites feature power, water, sewer, cable and Internet access (Additional charges apply for Internet access). These secluded, lush accomodations are private, back-in sites, and feature a level paved pad, Coquina rock bed, picnic table and charcoal grill, plus all the magic of Disney just steps outside your front door. Nearby, you will find deluxe, air-conditioned Comfort Stations with restrooms, private showers, ice dispensers, laundry facilities and pay phones. If you are bringing your pets, be sure to request a pet-friendly campsite. (Restrictions and charges apply.)
The following equipment is best suited to our Preferred Campsites:
- Motor Home
- Motor Home with Additional Tents
- 5th Wheel
- 5th Wheel with Additional Tents
- Travel Trailer
- Travel Trailer with Additional Tents
- Truck/Van Camper
- Truck/Van Camper with Additional Tents
- Pop Up Camper
- Pop Up Camper with Additional Tents
Premium Campsites
Premium campsites feature hookups for water, power, sewer, cable and Internet access. (Additional charges apply for Internet access.) These secluded, big-rig-friendly accommodations are only steps away from Disney magic and provide all the room and amenities RVers are looking for, plus a little extraincluding a large level paved pad, upgraded picnic table and grill, as well as prime locations in the Resort. Nearby, you will find deluxe, air-conditioned Comfort Stations with restrooms, private showers, ice dispensers, laundry facilities and pay phones. If you are bringing your pets, be sure to request a pet-friendly campsite. (Restrictions and charges apply.)
The following equipment is best suited to our Premium Campsites:
- Most big-rigs
- Motor Home
- Motor Home with Additional Tents
- 5th Wheel
- 5th Wheel with Additional Tents
- Travel Trailer
- Travel Trailer with Additional Tents
- Truck/Van Camper
- Truck/Van Camper with Additional Tents
- Pop Up Camper
- Pop Up Camper with Additional Tents