Config_dir vs filebeat.config.prospectors

Elastic Stack Beats
1

Documentation seems to suggest conf_dir can be used to set the external config directory.
However they can also be set using the following:

filebeat.config.prospectors:
enabled: true
path: configs/*.yml
reload.enabled: true
reload.period: 10s

What are the differences between both methods and what happens if both are set?
I know that the 2nd method allows the auto reading of new config files.

2

The difference is config_dir is not reread periodically if reload is enabled.
If both is set all configs are read and merged into a same config structure. But only the files under filebeat.config.prospectors.path are reread in case of reload.