These exceptional and high-quality stained-glass, leadlight windows were made around 1500. They illustrate the transition from the more static Gothic style to Mannerism. Both panels depict a figure defeating a dragon. One is Saint George, the other is the archangel Michael.
But how do you know who is who? If the figure has wings, it is definitely Michael from the Christian Bible. When the devil, disguised as a dragon, invades heaven along with other evil monsters, it is the archangel Michael who leads the angels in battle. Michael subdues the dragon with his sword and drives it, together with the other evil, out of heaven.
The legend of Saint George goes back to several stories from antiquity and the Middle Ages, but certainly features Christian symbolism as well. The Roman soldier Georgius (or George) happens to arrive in a city under the spell of a dragon demanding human sacrifices. George wounds and subdues the dragon, promising to kill it if the people of the city convert to Christianity. Consequently, thousands of people are baptized and George beheads the dragon with his sword. Here, the dragon symbolizes paganism.