Assumend that MOV is the acronym of Motor Operated Valve and ROV means Remote Operated Valve.
While ROV ia s generic term used to indicate an actuated (pneumatic, electric, hydraulic or other) valve which may be opened or closed from a distance by means of electric signal, MOV indicates a valve specifically actuaded by a motor actuator, usually electric.
So a ROV can be MOV.
As far as I know, there is no standard for acronyms axcept ANSI/ISA 5.1. so this case is considered an Industrial Standard.
ISA says:
2.8.2 Symbols different from those given in this standard and User’s choice letters when used, shall be fully described and detailed in the User/Owner’s standards, guidelines, or specifications and in drawing cover sheet legends and notes.
DAN