Q1: The difference is technical, based on the system by which the sync happens, not on what is synced. You should be running both tasks. They will be merged into one task to reduce confusion in next release.   Q2: This is currently not an option, I didn't think of this use case when I added the removals to the plugin. There will be an option to disable removals in the next release. As a temporary workaround you can disable Collection sync entirely.