Fungi are the eukaryotic, multicellular and heterotrophic organisms that are different from plant and animals.
The body of fungi consists of mycelium, fruiting body and spore. Mycelium is composed of threads like structure called hyphae. Fruiting body of fungi is the place where spore are produced. Spores are the reproductive elements of fungi through which new fungi is produced.
Genetic variation happens when one organism in the population mates with a genetically different organism. Same species, different genetics such as color or height/weight.