What’s the difference between teeth of animatronic dinosaurs and a dinosaur costume?
I don’t think there is a big difference between the teeth of the animatronic dinosaur suit and the teeth of the animatronic large dinosaur model in terms of appearance.

The soft one is harmless for the child.
Because they almost have the same appearance, but from the material side, the teeth of the dinosaur suit are made of silicone rubber, and the teeth of the large dinosaur model are made of epoxy resin, so one is soft and the other is hard.

hard dinosaur teeth
The purpose of doing so is to ease the net weight of the dinosaur suit itself, which makes the actors more skillful.