No, just the length of your RV (trailer, motor coach, 5er, pop-up). On Reserve America sites for State Parks, you use the RV length so the web site will filter out sites that are too short. It will only return available sites that will accomidate whatever size you put in that field (here again, this is Reserve America which almost every State DNR web site is now utilizing).
Once you pull up the site you are interested in, it will give you the actual pad size and also the actual campsite total size. You may enter 40 foot RV. Sites for a specific State Park may return only 5 available spots for the dates you are considering.
Now go to Google Maps and look at the ariel imaging of the campground and find the site you are considering. It will give you a good idea for location of trees and such.
Now go back to Reserve America and pull up the details on the site. You will see an image of the site from the ground, and details may say, Pad size 10 x45, site size 60x30, water 20 yards, restrooms/showers 100 yards, etc.
Now, if the web site is a private campground, it's hard to say what that field may mean.