I am a float nurse that is often scheduled between the in-patient floors and the psych ER.
For inpatient, we too usually assign staff to specific tasks, as an LPN I am often either the med nurse or the milieu nurse (nurse on the floor with the patients, attending or even running groups and rec therapy). Med nurses have to check for signs of medication compliance, floor nurses often do the environmental and room checks- keeping patients out of rooms not their own, looking for contraband, watching visitors who might give contraband, watching meals for pocketed objects or hoarding. There are usually two RN's, one or two LPNs, and one or two HA. (Four to the unit, so the breakdown is technically 4 patients per staff for end of shift notes).
There are variances for things like adolescent units (age appropriate activities and groups, many more behavioral issues at play than psychiatric per capita), and geriatric and detox combines a lot of Mental Health with Med-Surg.
Its a bit different for our Psych ER. Again there are assigned jobs, LPNs with the milieu or meds, Charge RN, but here additional RNS to admit, discharge, and interview patients. There are also security officers posted and often special guest appearances by local law enforcement bringing in or taking out patients. It is much more fast paced, patients here are usually arriving in the middle or just post acute phase. (Also, a lot of people brought in for being under the influence and staying/doing the wrong thing while their BAC is jacked). A lot more restraints (often brought in as such), and PRN medication ordered.
For myself, I like the psych er most- You don't get sick of seeing the same faces every day (except for some frequent flyers) and you get to learn a little bit of everything. I do like the inpatient floors too, since by comparison you have a little more time to spend with patients that may respond to your nursing style. My mindset with these patients is pretty much to treat them like that one friend or friend's parent/sibling/grandparent that we all have somewhere, who somehow keeps getting in a rut and a run of bad luck, and you root for them and try your best to help them pull through. Some patients will love how you do your job, some hate you and like someone else's methods instead.
Before orientation to the floor, I had extra training on non-violent self defense, deescalation techniques, and restraint practices- four and five points. These things we review in service every year.
A lot of the main differences between psych and med-surg is that psych patients are usually not confined to bed and are instead mobile throughout the unit. The rooms do not have medical equipment, tv's or phones in them (all hazards to psych patients), and instead the phone and tv are communal in the lounge. Visiting happens in a specific room, not the patient room, and staff must watch all interaction. Lots of group activities, and of course there are some violent or grossly psychotic patients that will go after you for any reason, so there is an increased level of awareness for safety measures and locations of other staff members.