By skyforbes Years of misused definition has definitely affected the words "MMO" and "MMORPG". Now people mostly associate MMO the same as they do to MMORPG.
"MMO" means "Massively Multiplayer Online". That technically includes games like Rust, Once Human and Ark, etc.
"MMORPG" means "Massively Multiplayer Onine Role-Playing Game". This includes WOW, GW2, OSRS and FF14, etc.