A Villa is a Vacation Home, a home usually owned by an individual (rather than a corporation) and is 'let' out for Short Term Rental (STR) by the owner for stays of (usually) ranging from a few days to a month. All of the Villas listed on Orlando Exclusive Villas are self contained detached homes.
Be aware that Disney has started to refer to their self contained Condos as 'Villas'.
Some excerpts from
wikipedia help explain how the meaning of Villa has changed of late.
"[the word] Villa was extended to describe any large suburban house that was free-standing in a landscaped plot of ground....The villa concept lives on in the German speaking countries, southern Europe, Latin America and particularly on the American westcoast, where villas are associated with upper-class social position and lifestyle"