Several differences may not deal with the wording, but deals with support for a bike that weighs on minimum double what a conventional peddle only bike weighs. In a broader sense bike rack manufacturers do place a weight limit on their bikes for a reason, as a rule. While there are bike racks that costs 188 bucks and possibly works just fine, its important to look deeper into the general details of what someone might be carrying on them, whether you place the rack on your toad or on the back of your towed vehicle.
There are e-bikes that can weigh up to 80 pounds and then some. So if you place two e-bikes on a regular bike rack or an entry level e-bike rack, you do risk the loss of them and possibly additional harm to someone behind you when on the highway.
When you place a regular bike rack and two e-bikes beginning at 45 to 50 pounds each on a sewer hose bumper and head down the road, there is plenty of wiggling going on. Even manufacturers suggest that you don't do this.
A lot of manufacturers have actually converted to a more rigid receiver that mounts to the frame , probably because of lawyers and repeated issues with sewer hose tubes breakage. They have a very back tendency to rust from the inside and will break apart without anyone ever noticing a problem ahead of time.
Entry level e-bikes cost around 700 to 800 and can go up five thousands of dollars and then some. Each year they continue to improve the range for the batteries and in turn increase the weights when you put an upgraded one on a rack.