How to distinguish between carbon monoxide (CO) detector and carbon dioxide (CO₂) detector by detection value

Carbon Monoxide (CO) Detector : 
Normal value: 0–50 ppm
Warning value: 51–200 ppm
Danger value: 201–999 ppm
Special note: In an environment without carbon monoxide gas, it is normal for the detector to display 000 ppm.

Carbon Dioxide (CO₂) Detector : 
Normal value: 400–700 ppm
Warning value: 700–1500 ppm
Danger value: 1500–5000 ppm
Special note: In a well-ventilated environment, a carbon dioxide concentration in the range of 400–700 ppm is normal.