Setup script execution time – Magento 2
Updated: Aug 20, 2020
Magento setup scripts are used to create/alter table and insert/update data into table while installing /upgrading module.

Install prefix scripts are executed while running “php bin/magento setup:upgrade”.
Upgrade prefix scripts are executed while running “php bin/magento setup:upgrade”, it additionaly check right version to execute the logic.
I hope, it helps.