I've felt at times that ENFps are like IEIs turned inside out. Their sets of strong and weak functions is exactly same, only directed inversely. This creates some overlaps in strong and weak points. Being irrational, intuitive, tactical types they often face same kind of challenges in life (like streamlining their career path). This probably extends to other extinguishment types in general.
Easiest way to tell them apart is through intertypes: is LSE your "activator"? do LSIs feel like "conflit" types"? does ESE feel like "benefactor" in communication? Obstinate/yielding differences also tend to stand out - IEEs as "obstinate" types tend to be protective and formative of their interests and opinions, while IEIs simply get curious, and will dive into and readily share their interests with others:
http://wikisocion.org/en/index.php?t...haracteristics