Home Assistant adds a way to build a custom heating or cooling control around existing readings and actions. The template integration supplies its displayed state from templates and runs configured scripts when someone changes a mode or target temperature.
Petro31 adds setup through the Helpers screen or YAML configuration. Options cover temperature, humidity, fan modes, presets and air-direction controls. The person configuring the helper supplies the readings and actions behind the features they need; automatic temperature regulation depends on those configured actions.