how does search online for urls and search online for site lists work

i want to know how does search online for urls and search online for site lists work.
in the options-advanced-tool.
and how does these two Function often uses

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hope you know what i mean!!!

Look at the first video here https://forum.gsa-online.de/discussion/11/gsa-search-engine-ranker-video-tutorials-updated-8-17-2012

I think it is explained on the video