Ni is like the inner surface area of that sphere, focusing in on the central focal point.
Ne is like that central focal point, looking out all over the place at the inner surface area of the sphere.
As such, Ni is good at focusing; Ne is good at connecting disparate parts.
The con for each is that Ni will tend to focus on its point in the "selfish" manner of an introverted function, while Ne will jump from one topic to the next without necessarily coming to any resolution on any one of them (and possibly not seeing the thing as a whole).
Hence, Ni people are often accused of tunnel-vision, while Ne people are accused of not being able to focus.
Both accusations are true to some extent, varying by degree from individual to individual.