linear motion bearings do the linear motion but not rotational motion. Used the steel balls as roll element, they do the circulating motion on the several close raceways in the cylindrial
bearings.

linear motion bearings usually meet the following requirements:

move stably with friction. Do not crawl or vibrate

minor force need for them to do the linear motion between the shaft and shaft.

The requiremnts above or other different requirement can be met by using the different typs of linear motion bearings(close type, modified type, open type).