Giving food to the hungry, providing medical aid to the sick and imparting secular knowledge or information to the ignorant are generally taken to be acts of service to be rendered to others by a person who is service-minded. Offering any other help to the needy can also be included in this. But providing the basic or primary needs to the others is only a low type of service.
There is a higher level of service when somebody imparts knowledge to the needy and also training to the person to make him independent and self-reliant, and thus making him stand on his own legs.
But there exists a still higher level of service when a higher and a deeper knowledge is imparted which can be described as enlightenment or inward illumination.
In the two earlier cases, we enable a person to gain pleasure but here we equip a person to attain real happiness. We draw his attention to the deeper human problems and strengthen his means of understanding to realize what happiness is and how it can be enjoyed individually and collectively.