IMO it's the difference between a really strong piece of ceramic that happens to not break when you whack it with a hammer, and something like safety glass that

IMO it's the difference between a really strong piece of ceramic that happens to not break when you whack it with a hammer, and something like safety glass that shatters yet stays intact. The ceramic is robust, but with a big enough whack it'll shatter into a million pieces - but the fragility of the safety glass is known and prepared for to the point where it breaking doesn't lead to a complete failure.