I understand how an NT would have trouble putting a dividing line between N and T, but they refer to two completely different parts of what, ideally, is a single process. Intuition is a perceiving function. For us INTPs it functions as our tendency to look at the world and see patterns. It allows us to explore the interrelatedness of things. For INTJs it allows them to brainstorm about stuff they know. That's why INTJs are so good at application. Give them the information and they will always be able to come up with a potential use.
For thinking its just the opposite. We use thinking to look at the patterns we've observed and coordinate them into a system that explains how the universe works. INTJs use it on the world to see the rules by which things operate. This goes along with what I said earlier about being excellent at application.
For a fundamental difference between INTPs and INTJs think about this:
INTJs introvert their perception and extravert their judgment which helps them change the world based on their own ideas. I like to call them the great "improvers". In other words they imagine what is possible and then apply it. Because they don't extravert their perceiving ability, they are also are at risk of being fairly oblivious to anything they don't understand (a.k.a. people's emotions, differing values).
INTPs introvert their judgment and extravert their perception with makes them the great "comprehenders". In other words, we collect data from outside and organize it inside. On the flip side because we don't extravert our judging, we can fall into procrastination, where we never feel prepared enough to start something, and so we never do it.
Oh, I almost submitted without ever mentioning the poetry. Poetry doesn't have anything to do with feeling. Its all about introverted intuition. It just so happens that most successful poets are introverted intuiters with extraverted feeling to help them express themselves in a beautiful way or to refer to things that effect emotion or personal values. I believe Ogden Nash was an INTJ.
Sorry if I have a habit of taking a sledgehammer approach to questions. I don't believe that I've covered all the bases and I'm not certain that I'm right. I'm not really sure why the combination of introverted thinking and extraverted intuition makes me unable to stop talking about an idea once I get rolling
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