The propane brooders are meant to heat a large floor area at once. The birds can move closer or further away as needed. These are probably from commercial broiler or turkey barns where they have 1000's of chicks that are the same age. Too much for most of us, but not for Sally, or Wingstone or SilkieSensation, said the pot about the kettle.
The Plasson waterers are meant to be hooked up to a low pressure hose system. They automatically refill as needed. I have about a dozen of them and will be setting them up soon so I can quit messing with water buckets. They're another item used in commercial poultry barns.