Right-to-use ownerships are not deeded, and feature an expiration date, after which the owner can not utilize the resort.
The opposite of a fee simple ownership.
They are different from vacation clubs, which also do not carry a deed in that Vacation Clubs offer perpetual ownerships that do not expire.
Right-To-Use (RTU) timeshares can be described as a deeded ownership that expires at a pre-determined date. Disney timeshares are predominantly right-to-use ownerships and many properties in Mexico operate with deed expiration dates.
There are benefits and drawbacks to owning this type of ownership, and the choice between a perpetual ownership and a right to use ownership will be dependent of the type of traveler you are.