I have lived in houses equipped with a forced air gas furnace plus those with boilers.
There is a big difference between a oil furnace that uses air to transfer heat energy plus one that uses water.
A gas furnace requires a network of ducts that transfer the heated air to the many rooms plus pull out the stale air. As the air circulates through these pipes, it can pick up any dust, bacteria, mold spores or contaminants that are concealed inside plus spread them into the breathing air. The majority of duct systems have tiny holes, cracks plus imperfections that allow up to 30% of the heated air to escape. The operation of the ductwork is respectfully quite noisy. When the warm air flows out of the vents plus into the room, it naturally rises up toward the ceiling. It only drops down after it has cooled. The process is inefficient plus creates uncomfortable temperature fluctuations. A higher thermostat setting is necessary because the highest temperature is near the ceiling. A boiler uses water rather than air to transfer heat. There is a closed loop system that uses the same water over plus over again. It avoids spreading contaminants, makes no noise plus there are no energy losses due to leaks, then rather than getting blown in the room, the heat is infused into the air by way of a radiator, baseboard furnace or radiant floors. There are no drafts, no frosty spots plus the temperature everywhere in the room remains within more than two degrees of the thermostat setting. Boiler heating is more gentle plus doesn’t dry out the air. It allows for the simple set up of zone control. With a thermostat in each room, it’s possible to customize the temperature according to requirements, preference plus occupancy.