I find it odd that anyone would need to make the distinction. Are they perhaps trying to distinguish that for the child, it is not yet determined if it's e.g. a developmental thing that can be addressed (and thus might go away)? As for the language use in general, it's probably easier in my language, where the term literally is made up of the verb (or in some cases, the adjective). We don't really use any noun version of it. But e.g. on this sub, in English, I can say "stutterer" and have it make sense. It wouldn't in my own language.