Lubricant is basically an oil. There are bearings in a car or even a skateboard which requires lubircant so the metal will be able to control its temperature and avoid damage from friction and dirt.
A lubricant is a substance used for decreasing friction between two rough surfaces. It is mostly in a jely-like form. E.g. lubricating oil for machines.
If you are talking about Lubricating Oil. The majority of it will be will be a base oil which will be either a mineral or synthetic. There will then be additives which are chemicals which improve the...