The question is not only how many words the child has. What matters more is whether the child understands. When it follows instructions but cannot get words out, this is about producing speech. When it babbles fluently but does not respond to what you say, this is about understanding it. These are two different things and each leads somewhere else.
In the first case the weakened area is the one that assembles and sends out speech — the child knows what it wants to say and gets stuck only at saying it. In the second case the weakened area is the one that receives speech and makes sense of it — the sound arrives but does not connect to meaning. The exercises differ for each, which is why it is worth knowing which one it is.
The symptom profile for toddlers covers nine areas including both speech areas and shows which one is weakest. It does not look at speech alone — it also asks about attention, motor skills and hearing, which connect to speech more often than expected.