Hi CrystalKirk
I'll take a stab at it.
Think of the Index tab as you would the Index that appears at
the back of a printed book. For example, maybe you have a book on
Produce. You may know certain things as "Citrus" (Oranges, Lemons,
Grapefruits) but the actual word "Citrus" may not exist anywhere.
The index could have Citrus inside it, with the sub words of
Oranges, Lemons and Grapefruits. YOU get to decide which pages are
included in the Index. Thus, your user will only see what you
intended.
Search is just that. It's basically trawling through ALL the
words in the whole help file. So if your user searches for
"Orange", they see ANY and EVERY page listed that contains that
specific word. Therefore, your users are apt to see pages you never
intended. Maybe your book is related to a company that sells
Produce. Maybe their signature delivery vehicle is Orange in color.
So your user would find pages not even related to oranges.
Natural Language Search is only available with WebHelp Pro
output that is hosted on a RoboEngine. The goal with that was to
allow the user to simply ask a question as they might ask anyone.
The application then attempts to find matches to topics based on
keywords in the string. I'm not sure it ever worked out as well as
anyone hoped it would. I always figured it was something akin to a
child. Really rocky and didn't understand much at first, but as the
system "matured", and users asked questions and you saw reports and
tweaked accordingly, it would improve over time.
Hopefully that helps a bit. I also hope others will chime in
here to add their own experiences.
Cheers... Rick