Separationist secularism refers to the idea that governments should not recognise or concern themselves with religion at all (e.g. not fund religious schools, not allow legal exceptions on religious grounds, not partner with religious organisations, restrict religious expression in public or government spaces, etc.).
Accommodationist secularism refers to governments actively supporting religion in general without favouring a specific religious sect (e.g. guaranteeing freedom of religious expression, funding religious organisations, etc.).