This is an inaccurate comparison to VMWare Fusion. There are many features, e.g. Bootcamp partition virtualization, that virtualbox either forgot to mention or purposely excluded.
I suppose you could use a snapshot VMDK to put the FS changes into a file, which you could then keep or discard. No idea if VBox or even VMWare actually supports this behaviour. Nor can I think of any particularly good use for it!
Unless you mean that there is a difference between what merely happens to work and what the developers strive to ensure works. In this case, VirtualBox definitely "supports" using physical disks and partitions (though they describe it as an "advanced" feature).