'Hub Cap' or 'Wheel Cover'

A Hub Cap is a small Rubber or metal cap that covers only the hub or exposed axel, usually 1–3" in diameter, also called a 'dust cap', usually a press fit that snaps on.
A Wheel Cover is larger and covers almost the entire metal wheel, usually a fancy Chromed metal (or often plastic today) and held on with 3-4 spring clips, and covers both the center hub & the lug nuts, leaving only the rubber tire exposed.
The Wheel is the rigid circular metal frame that the rubber Tire fits onto and around. The circular outside Rim is welded to the center hub-axle-lug nut assembly, these two pieces now become a Wheel.

Both names are often used wrong and inter-changed, even in printed advertising; these are the common dictionary definitions.
Because we do make the rubber Hub Caps for these Garden Tractors, 1.25, 1.5, 1.62 & 2"ID sizes, I'm very familiar with these terms and the confusion, argument, misuse they often get.

Thanks Glen.