to what does bradburgy compare the scene at Montags house? what point is he making by using that description?

Which particular scene are you referring to? There are a few scenes at his house in the novel.

Part 3 Aslan

Bradbury compares the scene to a a circus or a carnival. This isn't a mere ordinary burning, it is made a spectacle. Bradbury draws on entertainment images like a big tent, ring man, and different circus acts. The absurdity of this burning is at the heart of the matter. Once the house is destroyed, the show is over.