The Gewa Pure violin Caseis made of polycarbonate,which is one of the strongest plastics in the world. It's actually used to make shatter-proof glass. Another good thing about plastic is that it's a lot more temperature-resistant compared to metallic cases.
In regards to the $150 violin case, we actually haven't heard of a carbon fiberglass violin case.With a lot of reputable brands that we work with, it's either a carbon fiber violin case, or a fiberglass violin case.
It's possible that the case combines these two materials (though the chances of that are extremely rare, and it would be a lot more expensive). But most likely, it just uses these words in its names, so that this case is easier to find on Amazon. For example, if someone searches for a carbon fiber violin case or fiberglass violin case, there's a higher chance of this case appearing in both searches.
For now, let's just assume that it is a carbon case. Carbon is a metallic material. It's not going to be as temperature-resistant as the Gewa Pure case.