INTP and INTJ are types that might be difficult to recognize initially, but they actually are two fundamentally different types.

INTP vs INTJ

The INTP is an analytical and creative thinker. The INTP thinks a bit outside the “rules” in order to come up with novel and unprecedented solutions. The INTP has little concern for “known truths” and will instinctively question the why behind any process. The INTP likes to build their own roadmap and in doing so tends to disregard widely accepted notions.
The INTJ is also an analytical thinker, but they are better with processes. Give an INTJ a goal, and they will think through and imagine steps they need to reach their end result. The INTJ looks for closure and ways to produce actionable results.
The INTP is more of a “troubleshooter” of already established systems and theories. They can fix bottlenecks and make things more efficient.
The INTJ is an “implementer” of systems and is able to bring a sense of order to chaos. They implement long term structure to their planning.
If you want to see a more in depth comparison of the differences between each type, it is best to focus on the four main functions.
The INTP Function Stack:
The INTJ Function Stack:
You can also help better identify the INTP vs. INTJ based on how they act when stressed.
The INTP under stress will use their weak Extraverted Feeling function a bit more. The normally reserved INTP may become a bit more agitated and “snappy” toward people and problems they can’t solve easily. Frustrated by their lack of ability to sort things out, they may become uncharacteristically emotional and moody.
The INTJ under stress will use their weak Extraverted Sensing function a bit more. The INTJ, typically a person with a lot of planning and foresight, will engage in a lot more impulsive behaviors. The INTJ may become stressed and can engage in risky activities like promiscuity, drugs and alcohol, or spending their money foolishly.