I'm no materials scientist, but here's been my observations in working with glass receptacles and bottles over the years:

Shape is a very important aspect of how strong glass things are. Perfume bottles (or any small bottle) tend to be stronger just due to the fact that they usually lack large, flat-ish areas and the thickness-to-surface area ratio tends to be higher.

For instance, if you drop a small glass soda bottle and a large glass soda bottle, the large one is far more likely to suffer damage than the small one.