To add, I think a big difference is where you're camping. My post above refers to California for the most part and at FS and COE public campgrounds. Private campgrounds are different as are campgrounds in other regions (as can be seen by the above posts).
Generally speaking, most of the FS and COE campgrounds in California have "general sites" that accept tents and/or RVs. These do not have any hookups. The campground often has a specific loop with tent only sites (if there is more than one loop in the campground). Occasionally, there will be an "RV loop" that offers at minimum electric hookups (rarely in FS campgrounds, more likely in COE campgrounds).
Coastal campgrounds are more likely to be divided by "RV sites" and "tent sites" with no "general sites" - that's because there is less privacy between sites and more views to disrupt with a rig. Forest campgrounds are more likely to be "general sites" mixing tents and RVs.