There are a lot of differences in facilties from campground to "resort" but what a commerial park, particularly, calls itself doesn't tell you a lot. I've been in campgrounds that have had more facilites than resorts and in RV parks that have not had full RV hookups.
Trailer parks, mobile home parks, manufactured housing enclaves are more for "permanent" residents, but depending on local housing codes may have a number of short term spaces designed for RV hookup rather than permanent hookups for mobile homes.
Places calling tnemselves campgrounds usually have at least a few sites for campers (i.e. folks setting up tents) which may be in a separate area, or may be the same sites made available for RV use.
Whether or not you make reservations depends on where and when you are going. Not all campgrounds take reservations, even some public RV parks do not. But in other places, near cities, popular destinations, or resort areas, the reservations culture is strong and RV sites get fully booked for some dates within minutes of the resevations window opening.