What is different about the way the genus and species names are written compared to the other taxa?

A genus may contain several species. To avoid confusion, since there are so many species, there are some that may share the same name, thus when writing the name of a species the genus is usually written along with it. Sometimes genus can be abbreviated with a single letter. You do not capitalized the species name, whereas the other taxon names are capitalized. Genus and species names are italicized but never with the other taxon names.