In asexual reproduction, the offspring come from a single parent, so no copulation occurs, and only one organism is responsible for the reproduction. In sexual reproduction, on the other hand, two organisms conceive or bear the offspring.
Asexual reproduction is the main mode of reproduction of certain types of organisms, such as bacterias, protists and archaea. The simple cell division is the basis for asexual reproduction. The nucleus in the cell divides into two and chromosomes in the original nucleus are copied so that one half gets the same exact DNA as the original cell, resulting in both halves becoming identical. Daughter cells are formed, and these daughter cells further divide. Asexual reproduction essentially creates a clone of the parent, as no other factor alters the genes or DNA of the parent.
In sexual reproduction, two types of cells are involved: the egg cell and the sperm cell. Unlike asexual reproduction, the offspring cannot be clones because two organisms are involved in this process. The offspring has its own genetic make-up, so it is unique, in a biological sense. In an evolutionary sense, while sexual reproduction is more complex, it ensures a certain amount of diversity thanks to the continuous melding and mixing of genes.