I am bipolar and for a few stretches I was moderately depressed. My cognitive abilities, energy, creativity, jump, all of that took a real hit. I felt like I was pushing myself twice as hard and to everyone else it looked like I was slacking. I was also pretty sad, stressed and felt like I was doing everything I could to just get through the day.
To outsiders who never knew me before, they would guess definitely introverted, maybe a lethargic ISFP, don't think I appeared depressed to most people.
As for difference between ENFP and ESFP, you would get a ton more responses on the ENFP forum.