ENTP - 1. Ne 2. Ti 3. Fe 4. Si
ENFJ - 1. Fe 2. Ni 3. Se 4. Ti
They share the judging functions of Ti & Fe but do not share each other's perception functions of Ne/Si [ENTP] and Ni/Se [ENFJ]. This means they will make decisions in a somewhat similar fashion but will differ in the way they perceive and gather information in the world.
The ENTP is going to prefer Truth [Ti - introverted Thinking] over Diplomacy [Fe - extroverted Feeling].
The ENFJ is going to prefer Diplomacy [Fe] over Truth [Ti].
The ENFJ is going to have a much greater distance between Fe and Ti due to those two being its respective dominant and inferior functions. The ENTP is more likely to switch between the two more often due to it being close to each other in it's 2nd [Ti] and 3rd [Fe] positions.
The ENTP will be appear a lot more esoteric and spontaneous than the ENFJ due to the dominant Ne [extroverted Intuition] preference over Ni [introverted Intuition] that cannot be switched off, and the inferior Si [introverted Sensing]. Also the ENTP has Fi [introverted Feeling] as it's least preferred function [7th] so they will most likely not understand and even be against the use of it. They tend to not put much stock into personal ethics. They are also more likely to appear like an ESTP due to their Role use of Se [extroverted Sensing] [8th function] meaning that at first glance they might come off as physically oriented and physically spontaneous until you spend more time with them and see that they are much more intellectually curious instead.
The ENFJ will appear more put together and business like due to their dominant judging function of Fe. ENFJ's Fe will be far more pronounced than ENTP's tertiary Fe. The ENFJ will constantly be doing things for other people around them and guiding people in many different situations. Another difference between the two types is ENFJ will prefer Ni [2nd] over Ne [6th]. They will appear less intellectually spontaneous and less silly and humor like and will be appear to have much more penetrating insight into situations. This leads them to play the role of a mentor a lot of the time due to their caring Fe nature mixed with the insightful Ni combo, where as an ENTP will look seem more like a absent minded teacher, a crazy genius due to the idea generation of Ne mixed with the logic seeking Ti, that's looking to correct logical fallacies.