INTJ wants a direction, INTP wants a better model
INTJs often move toward a strategic conclusion once the pattern feels solid enough. INTPs are more likely to keep examining the logic, refining the model, or reopening the question if a cleaner explanation appears.
Both love systems, but not the same part of the system
INTJs often think in terms of structure, leverage, and long-range execution. INTPs often stay absorbed in how the system works internally and whether the logic is elegant enough to trust.
Pressure changes the pace
When time is short, INTJs tend to move toward a plan and commit. INTPs may keep circling the assumptions longer because they want to be sure the frame itself is sound before they lock anything in.
Notice what you optimize for first
If your instinct is to get to the strongest direction and organize around it, you may be closer to INTJ. If your instinct is to refine the explanation until it feels internally correct, INTP may fit better.