The western dragon, very unlike the eastern counterpart, is usually portrayed as a symbol of evil. In the Middle Ages they were seen as destructive and deadly creatures. In biblical literature they were also seen a representation of Satan.
*Small illustration of an Western Dragon. My own concept of one.
Western dragons are usually portrayed as serpent-like creatures with the wings of a bat. In artworks they would bear long horns and spines running down their backs. Their appearance was more sinister than that of a eastern dragon.
*A serpent-like dragon made with mosaic
In modern media, the western dragon appears a lot in movies, shows, games and many more. They are usually portrayed as an enemy or evil creature.
*This is how most modern western dragons are depicted