Going by the first pic, the cover looks like plastic, so it's probably LEDs. Halogen lamps would need (more) venting holes and/or more "space" inside the housing.
And if your G4s are constantly dying, it's either "just" crappy quality with overdriven LEDs, or it could also be the housing. Halogens are a bit more heat resistant, so if you don't have enough ventilation the LEDs just cook themselves to death.