This is just my tale in life and may not be reflective of the experience you have had or will have in either specialty:
I loved hearing the stories from the schizophrenic patients that were on the psychiatric service in Akron Ohio. They were vivid, and interesting stories that kept the day interesting. There was also always a tension in the moment: what am I going to say that will help move this conversation forward to the goals I have in mind for this person's well being. It sounds simple but each person: psychotic, depressed, anxious, etc needed the conversation to flow differently. The interactions with the people were great and why I felt like I should be a psychiatrist.
In practice, it felt a lot more like medication management / adjustment and less about the stories. Psychosis is still psychosis, depressed is still depressed...the vivid story didn't change their management. The reasons I decided to go into psychiatry was no longer present.
In addition, there's were negatives for me that I hadn't anticipated:
(1) nearly everyone I thought I was helping, came back in with the same or similar problems. It felt like a revolving door.
(2)The CATIE trial had just come out and represented essentially the only true hypothesis driven, solid methodology science at that time. I read 3/4 of the suggested reading list of text books for residency in the first three months of intern year. I really didn't feel like there was much science to the practice of psychiatry then. At my heart, i always wanted to be a person who wielded science to better the community. This was lost.
(3) I am an emotional guy. I empathize fairly strongly and quite quickly. Unfortunately, over a short time, my emotional range was becoming blunted. I was much more even in my responses to my friends and family too. A wedding was a +1 excitement, a death wa as -1. It was changing me at a very central level.
(4) There was a patient who had a clear as day UTI (symptoms, plus positive urine gram stain) on the inpatient unit and I wanted to treat it. The staff doc wanted me to consult medicine for it. I get their point, they had been away from medicine of that sort for over 15 years and didn't want to make a mistake. Yet, to me, I wanted to be a practitioner of medicine who could at least diagnose and treat a urinary tract infection.
I knew I had to leave the specialty. I didnt' know what to leave it to, and certainly I was leaving behind some great things too: my coresidents were amazing and some of my fondest memories happened with them. The demands were not very great. I stayed up late having fun, I got my work done on time and to a really high quality, and I wasn't tired mentally or physically. Emotionally drained however.
Every time I looked up at the helicopter taking off the helipad, I felt an excitement. I wanted to be on that machine. I wanted to be a part of that. I should have considered EM at that moment, but I had to wait until Dr. Howie Mell (then an EM resident) told me: " You know, you dont' really act like an psychiatrist. You think more like an EM doc." More of his colleagues told me I shoudl switch too.
Just by chance, at that same time, it seems, one of the EM residents (Dr. William Shakespeare - descendent of THE Shakespeare) was in the process of switching to anesthesia. This is relevant, because I didn't get any interviews for EM. I applied late in the ERAS process (only 1 month left in interview season) and I had failed a year in medical school and was a psychiatry transfer...you can imagine I was scared at my chances. Thankfully Dr. Sadosty seemed to see my potential and accepted me into the EM residency by offering me Dr. Shakespeare's position. It was a miracle.
One month into the training, I was caught up in the action. The science was overflowing and there is an endless amount of information to read and learn. I can read any specialty text or journal and find it interesting. I actually did get to make a difference and my patients didnt have to come back for the same problem again and again: UTI resolves, fractures heal, STEMI revascularized.
Everyday I get to hear great stories. I actually get to fix somethings. I get to read wonderful scientific articles and there is so much that I can't keep up. I go home physically and mentally exhausted, though emotionally I am back to empathizing with the people I care about the most. I still get to customize the way I communicate to achieve my goals but now I do it with various patients AND with my consulting services and inpatient services.
I am truly blessed to love what I do. I would do everything again (college, medical school, repeat a year, psych intern year, EM residency, fellowship...everything) if given the opportunity.
This probably didnt help you at all as it is quite unique to me, but its my story of psychiatry and emergency medicine.