Radiator valves incorporate a 15mm connection as standard from the valve to pipe in modern heating systems and designer radiators. As such, they are interchangeable in most cases.
That said, the positioning of the radiator inlets and pipework can influence whether or not they can be swapped over without issue. Basically, angled and corner valves can be interchanged easily, but these types can’t be discarded for H-block valves that require a middle connection inlet. Similarly, straight valves are only suitable for connection with radiators with bottom inlets.
For further insight, browse our blog, Are radiator valves universal?