Brown dwarfs are stars of low luminosity and low mass. They live for a very long time (tens of billions of years). White dwarfs are the end product of stellar evolution. These are hot compact objects with a mass approximately equal to that of the Sun and a density of 2 x 10 ^ 10 g / cm3. If the white dwarf is a single star, then it will gradually cool down. They have a low luminosity.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.