The fact that you seem to think of IQ scores as a reliable indicator of intelligence is very telling.
Depends how you interpreted it. Because there are many kinds of IQ, and it doesnt include creativity for example.
However, as a broad spectrum, it kinda works.
When you compare a 110 to 120 IQ person, you'll see noticeable differences. Mainly in the ability to learn and understand, but there is some correlation to the general intelligence of a person.
I'll give you an example. Students with an IQ under 116 wont finish a scientific master with difficult mathematics, because of the inability to understand and reproduce the math lessons.
The opposite is not true. There are persons who are incredibly gifted in pure mathematics, but that doesnt automatically make them generally intelligent. Beeing below 116IQ however, makes you be lesser intelligent.