Disclaimer: one of the ISFPs I'm discussing did have some mental health shit going on, so some of her traits are a bit exaggerated and she might not be the best representation of ISFPs in general.
I've had a few experiences and close friendships with both types, but it's been a while since I've interacted with those groups. From my memory there are three main differences I noticed between INFPs and ISFPs.
First and foremost, the ISFPs were far more concerned with their appearances. By no means am I saying that ISFPs are vain, nor am I implying that INFPs don't look nice. I'm just saying that, overall, INFPs didn't agonise over their physical appearance as much as the ISFPs. It was important to the ISFPs that they looked nice. It wasn't as much of a priority for INFPs.
Secondly, the contents of our conversations had some subtle differences. Similar to my ISTP dad, ISFPs would often comment on things that they could see/hear/smell/etc. at that particular point in time. If there was a cool cloud formation, they'd point it out. If something had a slightly abnormal texture, they'd let me know. INFPs either didn't notice these things or didn't feel the need to comment on them. ISFPs were more focused on the physical world around them and would frequently point things out.
This final point may cause some disagreement, because it comes across as a criticism and I'm not sure how to word it. Generally, I found that ISFPs were more prepared to believe things without considering other options. If it made sense to their internal assumptions about the world, then it didn't seem to occur to them to think about alternative possibilities. In this sense, I suppose, INFPs were readily open-minded about alternative explanations, whereas ISFPs could be quite closed off and would need more time to consider.
I've had a few experiences and close friendships with both types, but it's been a while since I've interacted with those groups. From my memory there are three main differences I noticed between INFPs and ISFPs.
First and foremost, the ISFPs were far more concerned with their appearances. By no means am I saying that ISFPs are vain, nor am I implying that INFPs don't look nice. I'm just saying that, overall, INFPs didn't agonise over their physical appearance as much as the ISFPs. It was important to the ISFPs that they looked nice. It wasn't as much of a priority for INFPs.
Secondly, the contents of our conversations had some subtle differences. Similar to my ISTP dad, ISFPs would often comment on things that they could see/hear/smell/etc. at that particular point in time. If there was a cool cloud formation, they'd point it out. If something had a slightly abnormal texture, they'd let me know. INFPs either didn't notice these things or didn't feel the need to comment on them. ISFPs were more focused on the physical world around them and would frequently point things out.
This final point may cause some disagreement, because it comes across as a criticism and I'm not sure how to word it. Generally, I found that ISFPs were more prepared to believe things without considering other options. If it made sense to their internal assumptions about the world, then it didn't seem to occur to them to think about alternative possibilities. In this sense, I suppose, INFPs were readily open-minded about alternative explanations, whereas ISFPs could be quite closed off and would need more time to consider.