The facility I worked in didnt have a special dementia unit per se. All the residents were mixed in together, with the vast majority with varying levels of dementia and the doors locked at all times, but I did do clinicals in a place with a special alzheimers unit that was a little more laid back and less hectic than the rest of the facility.
My impression was that it was slower paced and calmer, with more one on one care, a quieter environment and an emphasis on quality of life over medical care. In terms of the residents themselves, they didnt seem any different than most nursing home residents aside from some of them were totally ambulatory and seemed fine physically. So they were less physically demanding and easier to transfer.
I think once they deteriorated and needed more heavy care they were moved out of that unit in most cases. That kiind of unit can be difficult in that you will have residents who may be faster and stronger than your typical nursing home patient, which can make them more of a danger to themselves and staff.
Over all I actually preferred the regular facility, as I liked the faster pace and thought it helped the shift go by faster.