I think the easiest way to tell the difference between Ni and Ne is to pair them up with their opposing Sensate functions.
- Extraverted Sensation (Se) says that the observable world is filled with wonderful stimuli, and all you have to do is let yourself react to it. No need to think, just react. The meaning of something is what your gut tells you you should do in response. If it's not here or not now, it's not real.
- Introverted Intuition (Ni) says that the observable world is arbitrary and deceitful, and not representative of all the possible interpretations of itself. You have to liberate yourself from these arbitrary interpretations by considering all possible interpretations, or you will risk being led astray.
- Extraverted Intuition (Ne) says that everything in the observable world is connected to a greater context, and it allows you to make contextual connections between this object and another one. Through this act of discovery, we become aware of greater possibilities for meaning, knowledge or action.
- Introverted Sensation (Si) says that the observable world is so overwhelmingly filled with stimuli and randomness that you need something stable to focus on, or you'll just be permanently overwhelmed and confused.
A nice method of telling the difference is to just consider the difference between Introverted and Extraverted Perception:
- Ne is open-ended and led by observation
- Ni is closed-off and not led by observation
Well, you know I disagree conceptually (I don't think information collecting (perceiving) functions are so deterministic), so I'll just present my thoughts:
First of all, it's impossible to define a perceiving function outside of the context of its associated judging function. Perceiving functions are the "memory" of the cognitive system, so to speak: it is how and where bits of sensory information are "held" to be processed by the judging function. Perceiving functions take in, support, then store the sensory data within the harder memory functions.
Sensing is the lossless version of this process (like a FLAC audio file). It takes input data in, handles it and stores it holistically. The benefit of this is that recollections are much more accurate and full of detail. Details are rarely overlooked or forgotten, and consistency/coherency maintained because of the completeness of the dataset. The downside is that these "big pictures" that are taken in require a lot of storage space within the long-term memory banks. As such, because of the constant need to place new information within these banks, the big matrices of information that the judging function deems unnecessary constantly must be disposed of (forgotten).
Intuition, on the other hand, is the lossy version of this process (like an MP3). It takes the input data in, handles it and stores it as a set of component parts. The benefit of this is that the data can be handled and stored much more efficiently, since rather than many sets of "big pictures" that need to be Judged, you have these individual bits of data, and the judging process only needs to clean up the redundant parts. The downside is that it recollects and interprets through constant fitting of those stored data points together, and this process can lead to some severe distortion.
As such, there really isn't any extraverted or introverted perceiving. It all has to do with what your judging function handles the perceptive data. If you have introverted judging, then the perceiving function appears "extraverted", because the internal judging function needs a constant flow of external data to keep from starving itself. When starved of this data, the judging function will attempt to compensate by using whatever sensory data is within, that is, previously processed by the judging data. For example:
Ne dom/aux: the "Si" tert/inf is the internal recollection of the initial N/Ji processing, brought together once again through the Ji function. Bigger assembled chunks of data are tied together through Fi/Ti, and this leads to much less effective results, since the sets of data are too broad to connect as well as the smaller ones brought in through Ne.
Se dom/aux: the "Ni" tert/inf is the internal dissection of the initial S/Ji processing, divided into its various parts through the Ji function. Since the big sets of sensory data are too large and unwieldy to handle for more than a short period of time by the Ji function (the "gut instinct" aspect), it then focuses in on smaller portions of the set, trying to come to either Fi or Ti-based conclusions about them ("If Coach would have put me in in '83, everything would have been different"). The problem is that the only dissembled data is within that one sphere, and that these conclusions do not factor in other, more distantly related variables.
If you have extraverted judging, then your perceptive function will appear introverted. This is simply because the external judging function needs an internal basis from which to operate. "Si" just bases this on big sets of data, and "Ni" bases this on small sets of data. When dealing with incompatible data, the Je will have no internal basis for comparison, and will thus have to compensate externally. So:
Si dom/aux: More than anything, Si immediately allows for Je to notice inconsistency, because it holds those big chunks of data (combined auditory, visual, gustatory, olfactory, tactile and emotional sensations) and lets Je compare them holistically to one another, and thus understanding immediately what's different between the two sets. If a situation is entirely unprecedented, and there is no means of comparison, the Je will do whatever it can to bring that situation back to something it can work with internally, also known as tert/inf "Ne".
Ni dom/aux: Ni splits data up. It keeps splitting them up until Je starts putting them back together. When Je puts them back together, unusual and previously unnoticed patterns develop, which seem
de novo since they are externally consistent (either on Te or Fe terms), but there was no means of knowing this before the data was broken apart and reassembled subconsciously. When the data is understood too discretely to further analyze, Je will then act on the outside world in an attempt to come up with more information that can be further processed, that is, tert/inf "Se".