Okay kiddo, so the international phonetic alphabet is like a secret code that helps people write down how words sound. But sometimes, people can't agree on how a certain word should be written down or pronounced.
So, some symbols in the international phonetic alphabet are no longer used because they were confusing or not helpful. Sort of like how we don't use typewriters anymore because computers are much easier and faster to use.
And then there are symbols that some people might use, but aren't officially part of the international phonetic alphabet. It's kind of like if you made up your own secret code with your friends, but not everyone else knows how to read it.
Does that make sense, kiddo?