A radiation survey meter (like the BNC Model 907) measures overall radiation dose or count rate — it tells you how much radiation is present but not what type of isotope is causing it. An isotope identifier (RIID) goes further by analyzing the energy spectrum of the radiation to identify the specific isotope. Survey meters are ideal for health physics and contamination screening; RIIDs are used when source characterization and threat assessment are required. Many field teams use both tools in combination.