Writing a component for Luxtronik Heatpumps

I’m testing the luxtronik which is waiting for merge into hassio. Everything is working fine so far.

Can someone explain for me what the “group: calculations” keyword is used for.
I see on some previous examples that some people are using group, and some are not.
Is this the right way to format configuration.yaml?
Also what is the difference between sensors and binary sensors?

sensor:
  - platform: luxtronik
    scan_interval: 60
    sensors:
      - group: calculations
        id: ID_WEB_Temperatur_TVL
        friendly_name: Temperature Tur
        icon: mdi:thermometer
      - group: calculations
        id: ID_WEB_Temperatur_TRL
        friendly_name: Temperatur Retur
        icon: mdi:thermometer
      - group: calculations
        id: ID_WEB_Sollwert_TRL_HZ
        friendly_name: Setpunkt Retur
        icon: mdi:thermometer
      - group: calculations
        id: ID_WEB_Temperatur_TA
        friendly_name: Temperatur Ute
        icon: mdi:thermometer