Glass is largely transparent to incoming solar radiation, which warms whatever is inside the greenhouse.  If the greenhouse had no walls (like the atmosphere), warmed greenhouse air would rise by convection and escape out via the open sides, and heavy cooler air near to the ground would flow in to take its place.  This open "greenhouse" would stay close to outside temperature.

What causes a real greenhouse to warm is the solid transparent roof and the closed walls.  The glass roof welcomes incoming solar radiation, but the solid enclosure prevents this warmed inside air from escaping.

In a real greenhouse, operators shut vents to prevent warm air from escaping (or open them when they wish to lower the inside temperature).  They also pump CO2 into their greenhouses to encourage plant growth (but the Anti-Greens want to starve plants by restricting CO2).

Earth's atmosphere has no firm roof or walls.  Solar heating at the surface just causes that hot air to rise, and it cools either by radiation or adiabatic expansion.  It is replaced by cooler air.

Earth is not a greenhouse.

Image: RawPixel.