The answer to 'smoke detector vs' is that smoke detectors and carbon monoxide (CO) detectors are both important safety devices for the home, but they serve different purposes. Smoke detectors alert you to the presence of smoke, which is an indication of fire, while CO detectors alert you to the presence of carbon monoxide, an odorless, colorless gas that can be deadly.
Smoke detectors use sensors to detect smoke particles in the air and sound an alarm to warn you of a potential fire. They are an essential safety feature in every home and should be installed on every level, including the basement and attic. CO detectors, on the other hand, use electrochemical sensors to detect the presence of carbon monoxide, which can be produced by malfunctioning fuel-burning appliances like furnaces, water heaters, fireplaces, and stoves. Both types of detectors are relatively inexpensive and can save lives, so it's recommended to have both installed in your home.