The right one is the door bell. I am guessing the left one is the siren
Other way around. The left device, the one in the photo without the cover on it with the three screw terminals, is a doorbell chime.
The right one in your image is a siren. A wired piezo siren can be used but only lower current draw ones. Would need to pop open the siren to check the model number for electrical characteristics.
See image below from the GC2 manual, page 15.
