bc the whole system that emerges out of your pre-dominant perceptual mode makes no sense if you take away this facet of perception.
cascadeco and jaguar pretty much covered the differences from a conceptual and a more behaviorial process. i think of Ni as cascadeco says, Ni is interpolation internally and Ne is extrapolation externally. Ne intelligence is stored outside of itself, the ability to overlay, superimpose objects, branch, recognize possibilities, infer, etc. Ni symbolizes everything internally, synthesizes, rotates and processes and sifts details. the intelligence of the imagination worn on the outside when merged with the environment vs worn on the inside in the world of symbolic representation (read: language systems).
we take the relationships inward and then walk along them internally in a super up close zoomed in detailed way. we lose track of the big picture bc we are soooooo focused on intricate relationships and how we can better intergrate them, adjust them, recognize their interconnections, potential meanings, etc. Ne is the opposite, it zooms into the relationships around it and uses all the information to get the flow, feel where the energy is moving, locate the basic pattern and pick up on it before it gets there. it is so anticipatory, it merges with the environment, imagines the possible directions of movement, expansion, and creation from any perceptual CENTER (not object).
Ne would get how to play the game, would imagine what it would feel like to be any PARTICULAR play in the game. Ni would imagine the whole SINGULARITY of the game itself.
Ti sometimes looks like Ni bc Ti painstakingly reorders everything into one single strand of causal chain that becomes singular when it keeps spiraling forever.