Bearing Cleaner refers to the actual fluid that will help clean and condition your bearings. Unlike other solutions, these cleaners are specially designed for use on bearings. Cleaning Units go by a number of different names (i.e. Wash, Spa, System) and are designed to help make the cleaning process easier by securely housing the bearings while the cleaner does it's magic. Cleaning units are not required but are very convienent to use. Cleaners are not always included with cleaning units so be sure to check the product descriptions for details.