I've created a multiboot pendrive with a couple of Linux distributions by using the YUMI tool from pendrivelinux, and by default it extracts the content of the chosen operating system's ISO on a dedicated folder in the destination pendrive; it can also direclty load ISOs stored on the pendrive. Quoting from the site:
Contrary to MultiBootISO's which used grub to boot ISO files directly from USB, YUMI uses syslinux to boot extracted distributions stored on the USB device, and reverts to using grub to Boot Multiple ISO files from USB, if necessary.
From the practical point of view, what are the differences between these two methods? Choosing one over another affects performance or has some other advantages?
The statement above seems to suggest that an extracted distro is a better choice than one run directly from an ISO file (since the latter is used only "if necessary"), but why? What are the benefits?
I'm more interested in system performance or differences after it has booted, rather than the capabilities of Syslinux Vs Grub. In other words, how it is different a system booted from an ISO to another booted from a directory where it was extracted?