Thanks. I have that as an Appendix in this Manual, and was looking for a more detailed description of "frugal" besides what I stole from the document above:
A frugal install is similar to running a live cd or live usb, except that it is running from a hard drive.
Advantages of frugal:
space is saved (installation to hard drive typically is 4 times the size of the iso, whereas with frugal it is the size of the iso).
Frugal from hard drive is faster than live usb and live cd.
great for testing (once set up).
I included that in the Appendix section, and maybe that is enough.