Three examples of the range of variations in life forms:
– Ants, cockroaches, spiders, houseflies, etc. live in the same building. They look entirely different from each other yet all of them belong to arthropoda.
– Humans, monkeys, cats and dogs lives in the same neighbourhood. They look entirely different yet all of them belong to mammalia.
– A nearby park may show wide variety of plants; right from small grass to a giant banyan tree.