Try these:
GPWS:
http://www.boeing-727.com/Data/systems/infogpws.html.
The 'different modes' are detailed there.
EGPWS:
http://www.honeywell.com/sites/aero/Egpws-Home.htm - which you have already had. I'm ASSUMING you have fully explored link 2 so you know all about the different modes? (Have you read 'General Information'?)
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EGPWS has, amongst other things, a database of terrain - so assuming it knows where the a/c is (IRS/GPS/FMC) it can produce 'enhanced' warning of terrain problems, and also show the crew the elevations of terrain in their vicinity. It also has airports in the database so with accurate positional information it knows whether you are descending to destruction or making an approach on a known airport. It also introduces a few other modes (which are also in the link).