The answer to 'which is better smoke detector or' is that smoke detectors are generally better for home fire safety than carbon monoxide (CO) detectors. Smoke detectors are designed to detect smoke from fires, which is the leading cause of home fire deaths. They provide an early warning that allows occupants to safely evacuate the home. In contrast, CO detectors are designed to detect the presence of odorless, colorless carbon monoxide gas, which can be deadly but is less common than fire hazards.
Smoke detectors are also more affordable and easier to install than CO detectors, making them a more accessible safety option for most homeowners. That said, homes with fuel-burning appliances like furnaces, water heaters, or fireplaces should also have CO detectors to protect against the risk of CO poisoning.