Confused- lovelace: in config.yaml, or not?

I have seen some posts saying no, and some saying yes. What is the definitive answer. Do I need

lovelace:
  mode: yaml

in configuration.yaml, or not? I can’t see any difference.

Yaml mode is just an alternative to the UI, if not enabled, you can customize your frontend by clicking the three dots in the upper right corner of the frontend.