Degreasers are intended to remove oil, grease, oxides and handling contamination from equipment and assemblies, while a contact cleaner does the same thing specifically for electrical contacts.
A contact cleaner (also called electrical cleaner, switch cleaner, electrical contact cleaner, and (specific for automotive repair) battery terminal cleaner removes contamination from electrical contacts, the conductive surfaces of connectors, switches and other electrical and electronic components with moving surface contacts.