The number of species is not settled with some recognising 1 and others, including Kew (Plants of the World Online) recognising 6.
Mabberley recognises Eruca vesicaria subsp. sativa as the only species.
For those who say Eruca vesicaria and E. sativa are distinct species the only difference is that E. sativa sepals fall off sooner.
With only 1 species recognised here descriptions of the genus and species are the same.