Yeah, VACUUM only shuffles rows within a page, to maximize the amount of free space available for new data. VACUUM FULL essentially rebuilds the segment files

Yeah, VACUUM only shuffles rows within a page, to maximize the amount of free space available for new data. VACUUM FULL essentially rebuilds the segment files - it creates new files and shovels all rows from the old ones. In the past it was implemented differently, by actually moving rows (a bit like defrag tools in Windows) but that was very expensive and inefficient.