The reason between the two is sweeter heaters are larger, and way more expensive. The coops each have a heater in them already, both electric, one oil-filled, and the other more like a small furnace installed into a wall. These heat the entire coop(s). Both keep the coops to around 40-45°F all winter. Sweeter Heaters or Cozy Coops only heat the area in direct proximity of them.
It's the growout pens I'd never have been able to keep chicks in for the winter without
something in there. They don't need much because those hutches are like dog houses, so they run in when they get cold, then back out to frolic in the pen.
This is an example of one. The others are similar but like square boxes and not this fancy.
View attachment 4226615View attachment 4226616