Both are licensed under California Title 22 by the Community Care Licensing Division (CCLD), but they serve different populations and that changes which license you actually need.
Adult Residential Facility (ARF): provides 24-hour non-medical care and supervision for adults age 18 to 59 who have a physical or developmental disability, a mental health condition, or a similar limitation, but who don't need nursing-home-level medical care. ARFs are often connected to county behavioral health programs and skilled-nursing-facility step-down placements.
Residential Care Facility for the Elderly (RCFE): provides non-medical care and supervision for adults 60 and older who need help with daily activities — sometimes called board-and-care or assisted living. RCFEs serve a retiree population, not working-age adults.
Both license types go through the same regulatory body (CCLD), require a certified administrator, involve the same general licensing steps (orientation, Part A & B application, pre-licensing inspection), and require a property that meets zoning and fire-clearance requirements.
The right license depends entirely on who you intend to serve, not on which one sounds more familiar. If you're planning to serve working-age adults with disabilities or mental health needs, that's an ARF. If you're planning to serve seniors, that's an RCFE. Some operators eventually run both license types, but each facility is licensed separately.