Asexual organisms have no or little variation. Their offspring are clones of the parent. However, variations in asexual organism occur when there are recombination, crossing over, and mutation.
Yes, sexually reproducing species show greater variation than asexually reproducing species. Offspring of sexually reproducing species have a combination of its parents' characteristics while offspring of asexual reproducing species are the clone of its parent. It has exactly the same composition as its parents.