While this topic, like most, is complex and nuanced, the table below shows, in matrix form, the primary differences between an RCFE (aka Assisted Living) and a Skilled Nursing Facility. We are hopeful the content will help your differentiate between the two.
A Residential Care Facility for the Elderly (RCFE) is the name used by California's Title 22 regulations define an RCFE as a "housing arrangement chosen voluntarily" by a resident or his guardian or other responsible party, where 75% of the residents are 60+, where care and supervision is provided to the residents in a manner consistent with their particular needs. In the vernacular, it is often called assisted living or supportive housing. It is non-medical in nature, and as mentioned above, is considered a "housing alternative" that provides care. It is not a medical facility, and is not classified as a health-care facility. The disparity is that despite these parameters, residents may be accepted and retained exhibiting many types of serious and chronic medical conditions.
By contrast, a Skilled Nursing Facility (SNF) is a facility licensed by California's Department of Public Health, licensed to provide 24/7 skilled professional medical services. It is a considered a medical facility, not a housing alternative.