They are different.
2020 FMC, 607.3.1 deals with Damper testing. Ceiling radiation dampers shall comply with the requirements of UL 555C or shall be tested as part of a fire-resistance-rated floor/ceiling of roof/ceiling assembly in accordance with ASTM E119.
2020 FMC, 607.6.2.1 deals with Ceiling radiation dampers. Ceiling radiation dampers shall be installed in accordance with the details listed in the fire-resistance-rated assembly and the manufacturer’s installation instructions and the listing.
UL 555C applies to ceiling dampers and ceiling air diffusers intended for use in HVAC systems where the airflow is operational at the time of a fire. Static ceiling radiation dampers are installed only in systems that are not designed to operate during a fire.
If the question asked is if a static ceiling radiation damper is" less than equivalent" to a dynamic one, the answer to that is "yes". If the system is designed so that air movement is not deactivated, then the dynamic ceiling radiation damper is required and the static one is not equivalent.
