The associations themselves are going in the right direction. The pendant is associated with something light, casual, simple and ordinary, while the necklace hides elegance and class. And indeed - this is the easiest way to distinguish these two models of jewelry.
How else can the differences be explained?
A pendant and a necklace differ in that pendants can be of different styles, from elegant to casual and even children's. Pendants can be made of string, they do not have to be entirely of precious metals. They are usually simple, for example with one pendant.
In turn, the necklace is a bit more exclusive jewelry, elegant, for special occasions, always entirely made of precious metal, sometimes with sophisticated shapes. In one word - the pendant and the necklace differ in character and workmanship.