Ramdasia community comprises of Julahas (Weavers) and Sikhs from this community are known as Ramdasia Sikhs. Ramdasia is a sub caste of Julaha (meaning weavers). The terms ravidasia and ramdasia are not synonymous and hence should never be used interchangeably as Ramdasias were originally weavers and not into leather making.
'Sikhism Does not believe in castism '
The Sikh Gurus tried their best to eliminate the caste system. In view of this, Langar was established, where all people from all castes, religions gather to eat food sitting together. Furthermore Guru Gobind Singh Ji gave all sikh men the lastname "Singh" and all Sikh women the lastname "Kaur" to remove castism as everyone is considered equal in Sikhism.
But slowly and slowly Sikhs of today have regained their old caste system inherited by Hinduism and use it to show superiority.