“All that is gold does not glitter” - J.R.R. Tolkien
“All that glitters is gold” - SmashMouth
Simple! If it glitters, it’s gold, but not all that is gold also has to glitter.
Thus, there exists gold that doesn’t glitter.
A is B, but B doesn’t have to be A.
But spongebob says “all that glitters is not gold” after he gets a new spatula and has a mental breakdown.