Why are greenhouse gases similar to a Greenhouse?

Like in a greenhouse, greenhouse gasses let radiation from the sun reach Earth (the 'inside' of the greenhouse) but won't let the Earth reflect radiation. This is exactly what greenhouses do. Through the glass walls, the sunlight can come in, but once the rays are inside, the heat is trapped. That causes (intentional) temperature rise in the greenhouse. These gasses also (most likely) cause a temperature rise on Earth.