Although chillstep can be clearly differentiated from louder, wilder dubstep, it uses the same techniques and electronic dance music influences, and whilst all recognise what chillstep is, not everyone within the dubstep world class it as a separate sub-genre, and instead think of it as a more laid back style of song that is still dubstep.
The genre from which chillstep was spawned originated in 1990s London and grew through the 2000s to wider reaches, which is when this more relaxed version was coined. However, as dubstep was already more relaxed than other types of rave music, it can be argued that original artists were already making what would later be called chillstep songs in their mellower moments, and that there is not necessarily a separation of artists, only in their song types.
Indeed, the most successful dubstep artists have produced some of the most popular chillstep songs, such as those listed on edmsauce: You & Me by Skrux, Worlds Apart by Seven Lions, Let It Be by Blackmill, Open Window by MitiS, Think About It by Phaeleh, I Need You by Rameses B, and I Remember by Deadmau5. All are major names in the genre, and even the biggest dubsteppers, such as Skrillex, have many tracks that are typical of the chillstep sounds.
As dubstep became more popular, the chilled parts were the most accessible elements to the mainstream, and so songs that could be termed chillstep crossed genres and entered the charts. Singer James Blake and band London Grammar are two exponents of this crossover success.
Even though chillstep deploys rumbling bass, doesn't remove the beats, and evokes a strong emotion, passion and beauty, it can also be used for passive listening, as its controlled effect can focus the mind and become a calming influence to help a listener either wind down or complete tasks more effectively. The flexibility in how this music can be beneficial maintains it as an effective sub genre.