Symbiosis is a type of interspecific relationship in which both organisms receive mutual benefit. Examples of symbiosis: hermit crab and sea anemone, nodule plants and bacteria, cap mushrooms and trees, lichens (symbiosis of fungus and algae)
Parasitism is a form of interspecific relationships in which some organisms exist at the expense of others, eating their blood, tissues, or digested food. Repeated use by a parasite of the host organism. Examples of parasitism: fungus and tree, dog and tick, parasitic worms and humans.
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.