What are differences in how a document appears when you view it in its
native format, e.g., Adobe Acrobat,and when you view it as HTML using
the link Google provides in search results?

Hi Nancyb, 

How Google will display a non-HTML file in HTML format depends on what
the original file had in it.  You may notice that some files display
just fine while others appear to be missing sections.  The reason is
that when viewed as HTML you lose the graphics contained in the
documents as well as the font embedding and precise text formatting. 
This isn't a big deal if the font being used is, say, Times Roman, but
if it's a special font for math equations or for musical notes then
the HTML version won't show anything where the original file contained
those characters.  This is due to the limitations of HTML which
doesn't provide for embedding fonts in web pages.  Ultimately this
means that if you don't have the font specified in a web page on your
local computer your browser will display it in a different font than
what the author intended.

If you have the application that can read the file in its native
format it's generally best to view the original.  View as HTML is
mostly useful if you're just trying to quickly browse through the file
to get a general idea of its contents.

There's a bit more information about the file types that Google can
interpret at this link: ://www.google.ca/help/faq_filetypes.html

I hope this helped you out.

Hibiscus

Thank you.